4B6I

Crystal structure Rap2b (SMA2266) from Serratia marcescens

4B6I の概要

• エントリーDOI: 10.2210/pdb4b6i/pdb
• 分子名称: SMA2266 (2 entities in total)
• 機能のキーワード: signaling protein
• 由来する生物種: SERRATIA MARCESCENS
• タンパク質・核酸の鎖数: 4
• 化学式量合計: 45898.37

構造登録者

Srikannathasan, V.,Hunter, W.N. (登録日: 2012-08-13, 公開日: 2012-08-22, 最終更新日: 2024-11-20)

主引用文献

English, G.,Trunk, K.,Rao, V.A.,Srikannathasan, V.,Hunter, W.N.,Coulthurst, S.J.
New Secreted Toxins and Immunity Proteins Encoded within the Type Vi Secretion System Gene Cluster of Serratia Marcescens.
Mol.Microbiol., 86:921-, 2012

PubMed Abstract: Protein secretion systems are critical to bacterial virulence and interactions with other organisms. The Type VI secretion system (T6SS) is found in many bacterial species and is used to target either eukaryotic cells or competitor bacteria. However, T6SS-secreted proteins have proven surprisingly elusive. Here, we identified two secreted substrates of the antibacterial T6SS from the opportunistic human pathogen, Serratia marcescens. Ssp1 and Ssp2, both encoded within the T6SS gene cluster, were confirmed as antibacterial toxins delivered by the T6SS. Four related proteins encoded around the Ssp proteins ('Rap' proteins) included two specifically conferring self-resistance ('immunity') against T6SS-dependent Ssp1 or Ssp2 toxicity. Biochemical characterization revealed specific, tight binding between cognate Ssp-Rap pairs, forming complexes of 2:2 stoichiometry. The atomic structures of two Rap proteins were solved, revealing a novel helical fold, dependent on a structural disulphide bond, a structural feature consistent with their functional localization. Homologues of the Serratia Ssp and Rap proteins are found encoded together within other T6SS gene clusters, thus they represent founder members of new families of T6SS-secreted and cognate immunity proteins. We suggest that Ssp proteins are the original substrates of the S. marcescens T6SS, before horizontal acquisition of other T6SS-secreted toxins. Molecular insight has been provided into how pathogens utilize antibacterial T6SSs to overcome competitors and succeed in polymicrobial niches.

PubMed: 22957938
DOI: 10.1111/MMI.12028

実験手法

X-RAY DIFFRACTION (1.95 Å)