Evolution and functional diversification of the small heat shock protein/α-crystallin family in higher plants
Evolution and functional diversification of the small heat shock protein/α-crystallin family in higher plants
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DOI：
10.1007/s00425-011-1575-9
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发表时间：
2012-06-01
期刊：
影响因子：
4.3
通讯作者：
ten Have, Arjen
中科院分区：
文献类型：
--
作者：
Gabriel Bondino, Hernan;Marta Valle, Estela;ten Have, Arjen
小热休克蛋白 (sHSP) 是在应激耐受中发挥重要作用的伴侣。它们由侧翼 N 端和 C 端区域的 α 晶状体蛋白结构域 (ACD) 组成。然而，并非所有含有 ACD 的蛋白质（以下称为 ACD 蛋白质）都是 sHSP，因为已知某些 ACD 蛋白质具有不同的功能。此外，由于尚未鉴定出所有 ACD 蛋白，因此目前的分类并不完整。通过 HMMER 分析筛选了总共 17 个完整的植物蛋白质组，以确定 ACD 蛋白的存在，并根据最大似然系统发育对鉴定出的 ACD 蛋白序列进行分类。分析组间和组内的差异，并确定功能限制水平。 ACD 蛋白有 29 种不同类别，其中 8 种包含经典 sHSP，5 种可能包含伴侣。其他类别包含功能未表征或表征不佳的蛋白质。 N 端和 C 端序列在系统发育类别中是保守的。系统发生学表明 CI sHSP 祖先的单一重复发生在单子叶和双子叶植物的物种形成之前。随后出现了一些最近的重复，导致出现了许多旁系同源。结果表明，sHSP 的 N 端和 C 端序列在类特异性功能中发挥作用，非 sHSP ACD 蛋白具有保守但未开发的功能，这些功能主要由 ACD 以外的子序列决定。
Small heat shock proteins (sHSPs) are chaperones that play an important role in stress tolerance. They consist of an alpha-crystallin domain (ACD) flanked by N- and C-terminal regions. However, not all proteins that contain an ACD, hereafter referred to as ACD proteins, are sHSPs because certain ACD proteins are known to have different functions. Furthermore, since not all ACD proteins have been identified yet, current classifications are incomplete. A total of 17 complete plant proteomes were screened for the presence of ACD proteins by HMMER profiling and the identified ACD protein sequences were classified by maximum likelihood phylogeny. Differences among and within groups were analysed, and levels of functional constraint were determined. There are 29 different classes of ACD proteins, eight of which contain classical sHSPs and five likely chaperones. The other classes contain proteins with uncharacterised or poorly characterised functions. N- and C-terminal sequences are conserved within the phylogenetic classes. Phylogenetics suggests a single duplication of the CI sHSP ancestor that occurred prior to the speciation of mono- and dicotyledons. This was followed by a number of more recent duplications that resulted in the presence of many paralogues. The results suggest that N- and C-terminal sequences of sHSPs play a role in class-specific functionality and that non-sHSP ACD proteins have conserved but unexplored functions, which are mainly determined by subsequences other than that of the ACD.