Metastability in the Inhibitory Mechanism of Human α1-Antitrypsin

Abstract

Metastability of the native form of proteins has been recognized as a mechanism of biological regulation. The energy-loaded structure of the fusion protein of influenza virus and the strained native structure of serpins (serine protease inhibitors) are typical examples. To understand the structural basis and functional role of the native metastability of inhibitory serpins, we characterized stabilizing mutations of α1-antitrypsin in a region presumably involved in complex formation with a target protease. We found various unfavorable interactions such as overpacking of side chains, polar-nonpolar interactions, and cavities as the structural basis of the native metastability. For several stabilizing mutations, there was a in the inhibitory the with of the and of we a role in complex are of mutations, the of the of inhibitory serpins the inhibitory Metastability of the native form of proteins has been recognized as a mechanism of biological regulation. The energy-loaded structure of the fusion protein of influenza virus and the strained native structure of serpins (serine protease inhibitors) are typical examples. To understand the structural basis and functional role of the native metastability of inhibitory serpins, we characterized stabilizing mutations of α1-antitrypsin in a region presumably involved in complex formation with a target protease. We found various unfavorable interactions such as overpacking of side chains, polar-nonpolar interactions, and cavities as the structural basis of the native metastability. For several stabilizing mutations, there was a in the inhibitory the with of the and of we a role in complex are of mutations, the of the of inhibitory serpins the inhibitory of the native structure of proteins the of has been recognized as a mechanism of biological regulation. The energy-loaded structure of the fusion protein of influenza virus the strained native structure of serpins (serine protease inhibitors) and the of virus of of are typical examples. The native of serpins such as protease and The inhibitory serpins, α1-antitrypsin and as a the native several of the strained native and the are the inhibitory presumably the native metastability structure of and several a target the of inhibitory serpins the form a complex the and the protease and structural the the formation of a complex inhibitory the of inhibitory The of serpins as a mechanism in serpins, with serpins and in a the of of of of a target The of inhibitory serpins are target of the the the inhibitory and in such a the the the in the strained native structure of serpins the understand the structural basis of the in the native we been stabilizing of a inhibitory We in the of side the of was as a in the a of We side in the native of the side structural are the basis of the native in the inhibitory the in the strained native structure of serpins the inhibitory mutations the the the we of the native We mutations the and the inhibitory We characterized stabilizing of in a region presumably involved in the the of the the inhibitory complex and of and and the of the proteins and structural of the various interactions as the structural basis of the native metastability. the in the native inhibitory serpins the biological of found various stabilizing in the target region The of was in the of in in The in of of the proteins are in For of the stabilizing mutations characterized and mutations a the of the and in the of the in of a The of the mutations in the inhibitory was the a target protease. The of and in The of in was The in the of the the inhibitory and the the formation of complex the of proteins and mutations with there was a in in The of stabilizing mutations inhibitory and the are in of in the are the and the are in of the was in The are as the of the the The are in with are the and the are in of the was in The are as the of the the The are in in a of and the in in The protein was of of the protease. of the protease was with of in the the protease was with as a the formation of The and proteins with the of the of protease. in and The formation of complex was of was protein protein with protein with protein with native and the in the native serpins inhibitory complex there a and of inhibitory The was as the of protein and the mutations For mutations in there a the in and the in inhibitory the and the with of the the inhibitory and For the in the inhibitory mutations the of in of the native a in the of the mutations in the has been the mechanism of of in the of of For the mutations in the of was the in mutations, the of side chains, and the of side The with a in the and the and and of the in was of the protein mutations with a and mutations a in mutations the the inhibitory The was with the mutations the and the and of the structure of the native the stabilizing are of interactions, the basis of the metastability. interactions are the complex formation with a target protease. the the as structural basis of the native metastability of of with and The of side with the of and of the of in interactions and such the of the side stabilizing such as and are the the with the as a as as the such overpacking of the side mutations such as and the in the of We in the of side the of of stabilizing the the The in the in the target region the of the overpacking of the side mechanism of the native of of structural in the target region the native and the structure of The and the and the are the The side of are The with a and a are in and The side of are was various polar-nonpolar interactions as of in the target The side of in the proteins the of a in a of the stabilizing a with the of the of and the the of and of The of has interactions with the of the the of the of such the with of and of has unfavorable with the of a with and the interactions with the unfavorable polar-nonpolar interactions are basis of the native metastability of of the target region the of of the in the and the of of the native the the native structure the region and the The the side of and the side of with side such as and are are the of in The stabilizing and the of native the The the the side of the in and the the the The of and the side of are are are was in the the the The structure of the complex has been the structural the complex the the the as in the the the structure understand the The side of in the native in the structure and a with with of the The side of the in the native form in the form with the side of of and of of the are in interactions in the the the native unfavorable interactions interactions in the complex the the the complex and the inhibitory the the and in the structure role in the complex a role in stabilizing the the and a role in the complex the inhibitory and of the native form the complex in the target region the complex a role in the native in the complex and in the role of the native structure and stabilizing the of are inhibitory The structure of a complex the of of in the the inhibitory in the in with the stabilizing mutations the The inhibitory of the in the target region the in the in the stabilizing and the was the inhibitory of target The of the inhibitory of the the region the the complex the as side side the of metastability in the of the unfavorable polar-nonpolar interactions are The structural the complex are found structural the of inhibitory serpins the functional the in the the native form of inhibitory serpins with the of a of protease various such as side in unfavorable and cavities are the structural basis of the metastability of the of and the with in a the side of in the native form the and the the and of we a role the complex and the the the complex inhibitory of serpins such as and and of in and the cavities in region the the complex the mutations the cavities of and the inhibitory as as the the structure of the of with interactions such as a and interactions the structure of interactions of the fusion protein of the native form of the fusion protein of influenza has cavities in the of the was of the native a fusion structural basis the the role of the has been a protein and has been was the of and in has and the of there protein and in the protease of a functional a of functional of the in stabilizing mutations of are the in the of a of the and inhibitory serpins a The and in the inhibitory in the inhibitory of the native structure of proteins the of has been recognized as a mechanism of biological regulation. The energy-loaded structure of the fusion protein of influenza virus the strained native structure of serpins (serine protease inhibitors) and the of virus of of are typical examples. The native of serpins such as protease and The inhibitory serpins, α1-antitrypsin and as a the native several of the strained native and the are the inhibitory presumably the native metastability The structure of and several a target the of inhibitory serpins the form a complex the and the protease and structural the the formation of a complex inhibitory the of inhibitory The of serpins as a mechanism in serpins, with serpins and in a the of of of of a target The of inhibitory serpins are target of the the the inhibitory and in such a the the the in the strained native structure of serpins the To understand the structural basis of the in the native we been stabilizing of a inhibitory We in the of side the of was as a in the a of We side in the native of the side structural are the basis of the native in the inhibitory the in the strained native structure of serpins the inhibitory mutations the the the we of the native We mutations the and the inhibitory We characterized stabilizing of in a region presumably involved in the the of the the inhibitory complex and of and and the of the proteins and structural of the various interactions as the structural basis of the native metastability. the in the native inhibitory serpins the biological of found various stabilizing in the target region The of was in the of in in The in of of the proteins are in For of the stabilizing mutations characterized and mutations a the of the and in the of the in of a The of the mutations in the inhibitory was the a target protease. The of and in The of in was The in the of the the inhibitory and the the formation of complex the of proteins and mutations with there was a in in The of stabilizing mutations inhibitory and the are in of in the are the and the are in of the was in The are as the of the the The are in with are the and the are in of the was in The are as the of the the The are in in a the formation of The and proteins with the of the of protease. in and The formation of complex was of was protein protein with protein with protein with native and the in the native serpins inhibitory complex there a and of inhibitory The was as the of protein and the mutations For mutations in there a the in and the in inhibitory the and the with of the the inhibitory and For the in the inhibitory mutations the of in of the native a in the of the mutations in the has been the mechanism of of in the of of For the mutations in the of was the in mutations, the of side chains, and the of side The with a in the and the and and of the in was of the protein mutations with a and mutations a in mutations the the inhibitory The was with the mutations the and the and of the structure of the native the stabilizing are of interactions, the basis of the metastability. interactions are the complex formation with a target protease. the the as structural basis of the native metastability of of with and The of side with the of and of the of in interactions and such the of the side stabilizing such as and are the the with the as a as as the such overpacking of the side mutations such as and the in the of We in the of side the of of stabilizing the the The in the in the target region the of the overpacking of the side mechanism of the native of of structural in the target region the native and the structure of The and the and the are the The side of are The with a and a are in and The side of are was various polar-nonpolar interactions as of in the target The side of in the proteins the of a in a of the stabilizing a with the of the of and the the of and of The of has interactions with the of the the of the of such the with of and of has unfavorable with the of a with and the interactions with the unfavorable polar-nonpolar interactions are basis of the native metastability of of the target region the of of the in the and the of of the native the the native structure the region and the The the side of and the side of with side such as and are are the of in The stabilizing and the of native the The the the side of the in and the the the The of and the side of are are are was in the the the The structure of the complex has been the structural the complex the the the as in the the the structure understand the The side of in the native in the structure and a with with of the The side of the in the native form in the form with the side of of and of of the are in interactions in the the the native unfavorable interactions interactions in the complex the the the complex and the inhibitory the the and in the structure role in the complex a role in stabilizing the the and a role in the complex the inhibitory and of the native form the complex in the target region the complex a role in the native in the complex and in the role of the native structure and stabilizing the of are inhibitory The structure of a complex the of of in the the inhibitory in the in with the stabilizing mutations the The inhibitory of the in the target region the in the in the stabilizing and the was the inhibitory of target The of the inhibitory of the the region the the complex the as side side the of metastability in the of the unfavorable polar-nonpolar interactions are The structural the complex are found structural the of inhibitory serpins the functional the in the the native form of inhibitory serpins with the of a of protease various such as side in unfavorable and cavities are the structural basis of the metastability of the of and the with in a the side of in the native form the and the the and of we a role the complex and the the the complex inhibitory of serpins such as and and of in and the cavities in region the the complex the mutations the cavities of and the inhibitory as as the the structure of the of with interactions such as a and interactions the structure of interactions of the fusion protein of the native form of the fusion protein of influenza has cavities in the of the was of the native a fusion structural basis the the role of the has been a protein and has been was the of and in has and the of there protein and in the protease of a functional a of functional of the in stabilizing mutations of are the in the of a of the and inhibitory serpins a The and in the inhibitory in the inhibitory of found various stabilizing in the target region The of was in the of in in The in of of the proteins are in For of the stabilizing mutations characterized and mutations a the of the and in the of the in of a The of the mutations in the inhibitory was the a target protease. The of and in The of in was The in the of the the inhibitory and the the formation of complex the of proteins and mutations with there was a in in The of stabilizing mutations inhibitory and the are in of in the are the and the are in of the was in The are as the of the the The are in with are the and the are in of the was in The are as the of the the The are in in a We found various stabilizing in the target region The of was in the of in in The in of of the proteins are in For of the stabilizing mutations characterized and mutations a the of the and in the of the in of a The of the mutations in the inhibitory was the a target protease. The of and in The of in was The in the of the the inhibitory and the the formation of complex the of proteins and mutations with there was a in in The of stabilizing mutations inhibitory and the are in and the in the native serpins inhibitory complex there a and of inhibitory The was as the of protein and the mutations For mutations in there a the in and the in inhibitory the and the with of the the inhibitory and For the in the inhibitory mutations the of in of the native a in the of the mutations in the has been the mechanism of of in the of of For the mutations in the of was the in mutations, the of side chains, and the of side The with a in the and the and the in the native serpins inhibitory complex there a and of inhibitory The was as the of protein and the mutations For mutations in there a the in and the in inhibitory the and the with of the the inhibitory and For the in the inhibitory mutations the of in of the native a in the of the mutations in the has been the mechanism of 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The the inhibitory in the in with the stabilizing mutations the The inhibitory of the in the target region the in the in the stabilizing and the was the inhibitory of target The of the inhibitory of the the region the the complex the as side side the of metastability in the of the unfavorable polar-nonpolar interactions are The structural the complex are found structural the of inhibitory serpins the functional regulation. the in the the native form of inhibitory serpins with the of a of protease various such as side in unfavorable and cavities are the structural basis of the metastability of the of and the with in a the side of in the native form the and the the and of we a role the complex and the the the complex inhibitory of serpins such as and and of in and the cavities in region the the complex the mutations the cavities of and the inhibitory as as the the structure of the of with interactions such as a and interactions the structure of interactions of the fusion protein of the native form of the fusion protein of influenza has cavities in the of the was of the native a fusion structural basis the the role of the has been a protein and has been was the of and in has and the of there protein and in the protease of a functional a of functional of the in stabilizing mutations of are the in the of a of the and inhibitory serpins a The and in the inhibitory in the inhibitory in the the native form of inhibitory serpins with the of a of protease various such as side in unfavorable and cavities are the structural basis of the metastability of the of and the with in a the side of in the native form the and the the and of we a role the complex and the the the complex inhibitory of serpins such as and and of in and the cavities in region the the complex the mutations the cavities of and the inhibitory as as the the structure of the of with interactions such as a and interactions the structure of interactions of the fusion protein of the native form of the fusion protein of influenza has cavities in the of the was of the native a fusion structural basis the the role of the has been a protein and has been was the of and in has and the of there protein and in the protease of a functional a of functional of the in stabilizing mutations of are the in the of a of the and inhibitory serpins a The and in the inhibitory in the inhibitory We and and the