Yu Benjamin, Kanaan Julia, Shames Hannah, Wicander James, Aryal Makunda, Li Yunfeng, Korza George, Brul Stanley, Kramer Gertjan, Li Yong-Qing, Nichols Frank C, Hao Bing, Setlow Peter
Department of Molecular Biology and Biophysics, UConn Health, Farmington, CT, United States.
Department of Physics, East Carolina University, Greenville, NC, United States.
Front Microbiol. 2023 Apr 11;14:1161604. doi: 10.3389/fmicb.2023.1161604. eCollection 2023.
2Duf, named after the presence of a transmembrane (TM) Duf421 domain and a small Duf1657 domain in its sequence, is likely located in the inner membrane (IM) of spores in some species carrying a transposon with an operon termed . These spores are known for their extreme resistance to wet heat, and 2Duf is believed to be the primary contributor to this trait. In this study, we found that the absence of YetF or YdfS, both Duf421 domain-containing proteins and found only in wild-type (wt) spores with YetF more abundant, leads to decreased resistance to wet heat and agents that can damage spore core components. The IM phospholipid compositions and core water and calcium-dipicolinic acid levels of YetF-deficient spores are similar to those of wt spores, but the deficiency could be restored by ectopic insertion of , and overexpression of YetF increased wt spore resistance to wet heat. In addition, and spores have decreased germination rates as individuals and populations with germinant receptor-dependent germinants and increased sensitivity to wet heat during germination, potentially due to damage to IM proteins. These data are consistent with a model in which YetF, YdfS and their homologs modify IM structure to reduce IM permeability and stabilize IM proteins against wet heat damage. Multiple homologs are also present in other spore forming and and even some asporogenous , but fewer in asporogenous species. The crystal structure of a YetF tetramer lacking the TM helices has been reported and features two distinct globular subdomains in each monomer. Sequence alignment and structure prediction suggest this fold is likely shared by other Duf421-containing proteins, including 2Duf. We have also identified naturally occurring homologs in some and species and in wt spores, but not in wt . Notably, the genomic organization around the gene in most of these species is similar to that in , suggesting that one of these species was the source of the genes on this operon in the extremely wet heat resistant spore formers.
2Duf因在其序列中存在一个跨膜（TM）Duf421结构域和一个小的Duf1657结构域而得名，在一些携带名为 的操纵子的转座子的物种中，它可能位于孢子的内膜（IM）中。这些孢子以其对湿热的极端抗性而闻名，并且2Duf被认为是这一特性的主要贡献者。在本研究中，我们发现缺失YetF或YdfS（两者都是含Duf421结构域的蛋白质，且仅在野生型（wt）孢子中发现，其中YetF含量更高）会导致对湿热和可破坏孢子核心成分的试剂的抗性降低。YetF缺陷型孢子的内膜磷脂组成以及核心水和钙 - 吡啶二羧酸水平与wt孢子相似，但通过 的异位插入可恢复该缺陷，并且YetF的过表达增加了wt孢子对湿热的抗性。此外， 和 孢子作为个体和群体，在使用依赖发芽受体的发芽剂时发芽率降低，并且在发芽过程中对湿热的敏感性增加，这可能是由于内膜蛋白受损所致。这些数据与一个模型一致，即YetF、YdfS及其同源物修饰内膜结构以降低内膜通透性，并稳定内膜蛋白以抵抗湿热损伤。多个 同源物也存在于其他形成孢子的 和 中，甚至存在于一些不产孢的 中，但在不产孢物种中较少。已经报道了缺少跨膜螺旋的YetF四聚体的晶体结构，并且每个单体具有两个不同的球状亚结构域。序列比对和结构预测表明，这种折叠可能为其他含Duf421的蛋白质所共有，包括2Duf。我们还在一些 和 物种以及wt 孢子中鉴定出天然存在的 同源物，但在wt 中未发现。值得注意的是，大多数这些物种中 基因周围的基因组组织与 中的相似，这表明这些物种之一是这种操纵子上的基因在极端耐湿热孢子形成者中的来源。
