Rajasekaran Mohan B, Hussain Rohanah, Siligardi Giuliano, Andrews Simon C, Watson Kimberly A
School of Biological Sciences, Health and Life Sciences Building, University of Reading, Whiteknights Campus, Reading, RG6 6EX, UK.
Sussex Drug Discovery Centre, School of Life Sciences, University of Sussex, Falmer, Brighton, BN19QJ, UK.
Biometals. 2022 Jun;35(3):573-589. doi: 10.1007/s10534-022-00389-2. Epub 2022 Mar 29.
EfeUOB/M has been characterised in Pseudomonas syringae pathovar. syringae as a novel type of ferrous-iron transporter, consisting of an inner-membrane protein (EfeU) and three periplasmic proteins (EfeO, EfeM and EfeB). The role of an iron permease and peroxidase function has been identified for the EfeU and EfeB proteins, respectively, but the role of EfeO/M remains unclear. EfeM is an 'M75-only' EfeO-like protein with a C-terminal peptidase-M75 domain (EfeO/EfeM family). Herein, we report the 1.6 Å resolution crystal structure of EfeM, the first structural report for an EfeM component of P. syringae pv. syringae. The structure possesses the bi-lobate architecture found in other bacterial periplasmic substrate/solute binding proteins. Metal binding studies, using SRCD and ICP-OES, reveal a preference of EfeM for copper, iron and zinc. This work provides detailed knowledge of the structural scaffold, the metal site geometry, and the divalent metal binding potential of EfeM. This work provides crucial underpinning for a more detailed understanding of the role of EfeM/EfeO proteins and the peptidase-M75 domains in EfeUOB/M iron uptake systems in bacteria.
在丁香假单胞菌丁香致病变种中，EfeUOB/M已被鉴定为一种新型的亚铁转运蛋白，由一种内膜蛋白（EfeU）和三种周质蛋白（EfeO、EfeM和EfeB）组成。已分别确定EfeU和EfeB蛋白具有铁通透酶和过氧化物酶功能，但EfeO/M的作用仍不清楚。EfeM是一种“仅含M75”的类EfeO蛋白，具有C端肽酶-M75结构域（EfeO/EfeM家族）。在此，我们报告了EfeM的1.6 Å分辨率晶体结构，这是丁香假单胞菌丁香致病变种EfeM组分的首个结构报告。该结构具有在其他细菌周质底物/溶质结合蛋白中发现的双叶结构。使用同步辐射圆二色光谱（SRCD）和电感耦合等离子体质谱（ICP-OES）进行的金属结合研究表明，EfeM对铜、铁和锌具有偏好性。这项工作提供了关于EfeM的结构支架、金属位点几何结构和二价金属结合潜力的详细知识。这项工作为更详细地了解EfeM/EfeO蛋白和肽酶-M75结构域在细菌EfeUOB/M铁摄取系统中的作用提供了关键支撑。
