Selective loss of cysteine residues and disulphide bonds in a potato proteinase inhibitor II family.

Disulphide bonds between cysteine residues in proteins play a key role in protein folding, stability, and function. Loss of a disulphide bond is often associated with functional differentiation of the protein. The evolution of disulphide bonds is still actively debated; analysis of naturally occurri...

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Main Authors: Xiu-Qing Li, Tieling Zhang, Danielle Donnelly
Format: Article
Language:English
Published: Public Library of Science (PLoS) 2011-01-01
Series:PLoS ONE
Online Access:http://europepmc.org/articles/PMC3073943?pdf=render
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author Xiu-Qing Li
Tieling Zhang
Danielle Donnelly
author_facet Xiu-Qing Li
Tieling Zhang
Danielle Donnelly
author_sort Xiu-Qing Li
collection DOAJ
description Disulphide bonds between cysteine residues in proteins play a key role in protein folding, stability, and function. Loss of a disulphide bond is often associated with functional differentiation of the protein. The evolution of disulphide bonds is still actively debated; analysis of naturally occurring variants can promote understanding of the protein evolutionary process. One of the disulphide bond-containing protein families is the potato proteinase inhibitor II (PI-II, or Pin2, for short) superfamily, which is found in most solanaceous plants and participates in plant development, stress response, and defence. Each PI-II domain contains eight cysteine residues (8C), and two similar PI-II domains form a functional protein that has eight disulphide bonds and two non-identical reaction centres. It is still unclear which patterns and processes affect cysteine residue loss in PI-II. Through cDNA sequencing and data mining, we found six natural variants missing cysteine residues involved in one or two disulphide bonds at the first reaction centre. We named these variants Pi7C and Pi6C for the proteins missing one or two pairs of cysteine residues, respectively. This PI-II-7C/6C family was found exclusively in potato. The missing cysteine residues were in bonding pairs but distant from one another at the nucleotide/protein sequence level. The non-synonymous/synonymous substitution (Ka/Ks) ratio analysis suggested a positive evolutionary gene selection for Pi6C and various Pi7C. The selective deletion of the first reaction centre cysteine residues that are structure-level-paired but sequence-level-distant in PI-II illustrates the flexibility of PI-II domains and suggests the functionality of their transient gene versions during evolution.
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spelling doaj.art-84d54d8b93dc44cab63cb779b7ffc4fb2022-12-21T17:49:39ZengPublic Library of Science (PLoS)PLoS ONE1932-62032011-01-0164e1861510.1371/journal.pone.0018615Selective loss of cysteine residues and disulphide bonds in a potato proteinase inhibitor II family.Xiu-Qing LiTieling ZhangDanielle DonnellyDisulphide bonds between cysteine residues in proteins play a key role in protein folding, stability, and function. Loss of a disulphide bond is often associated with functional differentiation of the protein. The evolution of disulphide bonds is still actively debated; analysis of naturally occurring variants can promote understanding of the protein evolutionary process. One of the disulphide bond-containing protein families is the potato proteinase inhibitor II (PI-II, or Pin2, for short) superfamily, which is found in most solanaceous plants and participates in plant development, stress response, and defence. Each PI-II domain contains eight cysteine residues (8C), and two similar PI-II domains form a functional protein that has eight disulphide bonds and two non-identical reaction centres. It is still unclear which patterns and processes affect cysteine residue loss in PI-II. Through cDNA sequencing and data mining, we found six natural variants missing cysteine residues involved in one or two disulphide bonds at the first reaction centre. We named these variants Pi7C and Pi6C for the proteins missing one or two pairs of cysteine residues, respectively. This PI-II-7C/6C family was found exclusively in potato. The missing cysteine residues were in bonding pairs but distant from one another at the nucleotide/protein sequence level. The non-synonymous/synonymous substitution (Ka/Ks) ratio analysis suggested a positive evolutionary gene selection for Pi6C and various Pi7C. The selective deletion of the first reaction centre cysteine residues that are structure-level-paired but sequence-level-distant in PI-II illustrates the flexibility of PI-II domains and suggests the functionality of their transient gene versions during evolution.http://europepmc.org/articles/PMC3073943?pdf=render
spellingShingle Xiu-Qing Li
Tieling Zhang
Danielle Donnelly
Selective loss of cysteine residues and disulphide bonds in a potato proteinase inhibitor II family.
PLoS ONE
title Selective loss of cysteine residues and disulphide bonds in a potato proteinase inhibitor II family.
title_full Selective loss of cysteine residues and disulphide bonds in a potato proteinase inhibitor II family.
title_fullStr Selective loss of cysteine residues and disulphide bonds in a potato proteinase inhibitor II family.
title_full_unstemmed Selective loss of cysteine residues and disulphide bonds in a potato proteinase inhibitor II family.
title_short Selective loss of cysteine residues and disulphide bonds in a potato proteinase inhibitor II family.
title_sort selective loss of cysteine residues and disulphide bonds in a potato proteinase inhibitor ii family
url http://europepmc.org/articles/PMC3073943?pdf=render
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AT tielingzhang selectivelossofcysteineresiduesanddisulphidebondsinapotatoproteinaseinhibitoriifamily
AT danielledonnelly selectivelossofcysteineresiduesanddisulphidebondsinapotatoproteinaseinhibitoriifamily