SigB 通过 Bc1009 调节非应激和热应激细胞中新的 SigB 调控因子成员的表达，揭示了其在蜡样芽胞杆菌中的替代作用。

SigB modulates expression of novel SigB regulon members via Bc1009 in non-stressed and heat-stressed cells revealing its alternative roles in Bacillus cereus.

机构信息

NIZO, Kernhemseweg 2, PO Box 20, 6718 ZB, Ede, The Netherlands.

Food Microbiology, Wageningen University and Research, PO Box 8129, 6700 EV, Wageningen, The Netherlands.

出版信息

BMC Microbiol. 2023 Feb 10;23(1):37. doi: 10.1186/s12866-023-02783-3.

DOI:10.1186/s12866-023-02783-3

PMID:36759782

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC9912610/

Abstract

BACKGROUND

The Bacillus cereus Sigma B (SigB) dependent general stress response is activated via the two-component RsbKY system, which involves a phosphate transfer from RsbK to RsbY. It has been hypothesized that the Hpr-like phosphocarrier protein (Bc1009) encoded by bc1009 in the SigB gene cluster may play a role in this transfer, thereby acting as a regulator of SigB activation. Alternatively, Bc1009 may be involved in the activation of a subset of SigB regulon members.

RESULTS

We first investigated the potential role of bc1009 to act as a SigB regulator but ruled out this possibility as the deletion of bc1009 did not affect the expression of sigB and other SigB gene cluster members. The SigB-dependent functions of Bc1009 were further examined in B. cereus ATCC14579 via comparative proteome profiling (backed up by transcriptomics) of wt, Δbc1009 and ΔsigB deletion mutants under heat stress at 42 °C. This revealed 284 proteins displaying SigB-dependent alterations in protein expression levels in heat-stressed cells, including a subgroup of 138 proteins for which alterations were also Bc1009-dependent. Next to proteins with roles in stress defense, newly identified SigB and Bc1009-dependent proteins have roles in cell motility, signal transduction, transcription, cell wall biogenesis, and amino acid transport and metabolism. Analysis of lethal stress survival at 50 °C after pre-adaptation at 42 °C showed intermediate survival efficacy of Δbc1009 cells, highest survival of wt, and lowest survival of ΔsigB cells, respectively. Additional comparative proteome analysis of non-stressed wt and mutant cells at 30 °C revealed 96 proteins with SigB and Bc1009-dependent differences in levels: 51 were also identified under heat stress, and 45 showed significant differential expression at 30 °C. This includes proteins with roles in carbohydrate/ion transport and metabolism. Overlapping functions at 30 °C and 42 °C included proteins involved in motility, and ΔsigB and Δbc1009 cells showed reduced motility compared to wt cells in swimming assays at both temperatures.

CONCLUSION

Our results extend the B. cereus SigB regulon to > 300 members, with a novel role of SigB-dependent Bc1009 in the activation of a subregulon of > 180 members, conceivably via interactions with other transcriptional regulatory networks.

摘要

背景

芽孢杆菌 SigB 依赖的一般应激反应通过双组分 RsbKY 系统激活，该系统涉及 RsbK 向 RsbY 的磷酸转移。据推测，SigB 基因簇中编码的 Hpr 样磷酸载体蛋白（Bc1009）可能在该转移中发挥作用，从而作为 SigB 激活的调节剂。或者，Bc1009 可能参与 SigB 调控子成员的亚组的激活。

结果

我们首先研究了 bc1009 作为 SigB 调节剂的潜在作用，但排除了这种可能性，因为 bc1009 的缺失不影响 sigB 和其他 SigB 基因簇成员的表达。通过比较蛋白质组学（通过转录组学支持）研究了 B. cereus ATCC14579 中 Bc1009 的 SigB 依赖性功能，wt、Δbc1009 和 ΔsigB 缺失突变体在 42°C 热应激下。这揭示了 284 种蛋白质显示出 SigB 依赖性蛋白质表达水平的变化，其中包括一组 138 种蛋白质，其变化也依赖于 Bc1009。除了在应激防御中起作用的蛋白质外，新鉴定的 SigB 和 Bc1009 依赖性蛋白质在细胞运动、信号转导、转录、细胞壁生物发生以及氨基酸运输和代谢中起作用。在 50°C 下进行致死性应激生存分析后，在 42°C 下进行预适应显示，Δbc1009 细胞的存活效力中等，wt 细胞的存活效力最高，ΔsigB 细胞的存活效力最低。在 30°C 下对非应激 wt 和突变细胞进行额外的比较蛋白质组分析显示，有 96 种蛋白质在水平上具有 SigB 和 Bc1009 依赖性差异：其中 51 种也在热应激下被鉴定，45 种在 30°C 时表现出显著的差异表达。这包括参与碳水化合物/离子运输和代谢的蛋白质。在 30°C 和 42°C 下的重叠功能包括参与运动的蛋白质，与 wt 细胞相比，ΔsigB 和 Δbc1009 细胞在这两种温度下的游泳试验中的运动能力降低。