Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, 310058, China.
Research Center of Siyuan Natural Pharmacy and Biotoxicology, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, 310058, China.
Sci Rep. 2019 Sep 25;9(1):13839. doi: 10.1038/s41598-019-50201-4.
In γ-proteobacterial species, such as Escherichia coli, the Arc (anoxic redox control) two-component system plays a major role in mediating the metabolic transition from aerobiosis to anaerobiosis, and thus is crucial for anaerobic growth but dispensable for aerobic growth. In Shewanella oneidensis, a bacterium renowned for respiratory versatility, Arc (SoArc) primarily affects aerobic growth. To date, how this occurs has remained largely unknown although the growth defect resulting from the loss of DNA-binding response regulator SoArcA is tryptone-dependent. In this study, we demonstrated that the growth defect is in part linked to utilization of oligopeptides and di-tripeptides, and peptide uptake but not peptide degradation is significantly affected by the SoArcA loss. A systematic characterization of major small peptide uptake systems manifests that ABC peptide transporter Sap and four proton-dependent oligopeptide transporters (POTs) are responsible for transport of oligopeptides and di-tripeptides respectively. Among them, Sap and DtpA (one of POTs) are responsive to the SoarcA mutation but only dtpA is under the direct control of SoArcA. We further showed that both Sap and DtpA, when overproduced, improve growth of the SoarcA mutant. While the data firmly establish a link between transport of oligopeptides and di-tripeptides and the SoarcA mutation, other yet-unidentified factors are implicated in the growth defect resulting from the SoArcA loss.
在γ-变形菌物种中，如大肠杆菌，Arc（缺氧氧化还原控制）双组分系统在介导从需氧到厌氧的代谢转变中起着主要作用，因此对厌氧生长至关重要，但对需氧生长可有可无。在兼性呼吸的希瓦氏菌属中，Arc（SoArc）主要影响需氧生长。迄今为止，尽管由于丧失 DNA 结合反应调节因子 SoArcA 而导致的生长缺陷依赖于胰蛋白胨，但这是如何发生的仍然很大程度上是未知的。在这项研究中，我们证明生长缺陷部分与寡肽和二肽的利用有关，并且肽吸收而不是肽降解受到 SoArcA 缺失的显著影响。对主要的小肽摄取系统的系统表征表明，ABC 肽转运蛋白 Sap 和四个质子依赖的寡肽转运蛋白（POTs）分别负责寡肽和二肽的转运。其中，Sap 和 DtpA（POT 之一）对 SoarcA 突变有反应，但只有 dtpA 受 SoArcA 的直接控制。我们进一步表明，当过度表达时，Sap 和 DtpA 均可改善 SoarcA 突变体的生长。虽然数据确凿地建立了寡肽和二肽的运输与 SoarcA 突变之间的联系，但其他尚未确定的因素与 SoArcA 缺失导致的生长缺陷有关。
