Qu Dehui, Zhao Xiaohui, Sun Yao, Wu Fan-Lin, Tao Sheng-Ce
Key Laboratory of Molecular Module-Based Breeding of High Yield and Abiotic Resistant Plants in Universities of Shandong, School of Agriculture, Ludong University, Yantai, China.
State Key Laboratory of Microbial Metabolism and School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China.
Front Microbiol. 2021 Mar 31;12:643951. doi: 10.3389/fmicb.2021.643951. eCollection 2021.
Ser/Thr phosphorylation by serine/threonine protein kinases (STPKs) plays significant roles in molecular regulation, which allows to adapt their cell wall structure in response to the environment changes. Identifying direct targets of STPKs and determining their activities are therefore critical to revealing their function in , for example, in cell wall formation and virulence. Herein, we reported that RmlA, a crucial L-rhamnose biosynthesis enzyme, is a substrate of STPK PknB in (). Mass spectrometry analysis revealed that RmlA is phosphorylated at Thr-12, Thr-54, Thr-197, and Thr-12 is located close to the catalytic triad of RmlA. Biochemical and phenotypic analysis of two RmlA mutants, T12A/T12D, showed that their activities were reduced, and cell wall formation was negatively affected. Moreover, virulence of RmlA T12D mutant was attenuated in a macrophage model. Overall, these results provide the first evidence for the role of PknB-dependent RmlA phosphorylation in regulating cell wall formation in , with significant implications for pathogenicity.
丝氨酸/苏氨酸蛋白激酶（STPKs）介导的丝氨酸/苏氨酸磷酸化在分子调控中发挥着重要作用，这使得细菌能够根据环境变化调整其细胞壁结构。因此，鉴定STPKs的直接靶点并确定其活性对于揭示它们在例如细胞壁形成和毒力方面的功能至关重要。在此，我们报道了鼠李糖生物合成关键酶RmlA是结核分枝杆菌中STPK PknB的底物。质谱分析显示，RmlA在苏氨酸-12、苏氨酸-54、苏氨酸-197处发生磷酸化，且苏氨酸-12靠近RmlA的催化三联体。对两个RmlA突变体T12A/T12D进行的生化和表型分析表明，它们的活性降低，细胞壁形成受到负面影响。此外，RmlA T12D突变体在巨噬细胞模型中的毒力减弱。总体而言，这些结果首次证明了PknB依赖性RmlA磷酸化在调节结核分枝杆菌细胞壁形成中的作用，对致病性具有重要意义。
