Brunsing Ryan L, La Clair Chandra, Tang Sharon, Chiang Christina, Hancock Lynn E, Perego Marta, Hoch James A
Division of Cellular Biology, Mail Code MEM-116, Department of Molecular and Experimental Medicine, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.
J Bacteriol. 2005 Oct;187(20):6972-81. doi: 10.1128/JB.187.20.6972-6981.2005.
The initiation of sporulation in Bacillus species is regulated by the phosphorelay signal transduction pathway, which is activated by several histidine sensor kinases in response to cellular and metabolic signals. Comparison of the protein components of the phosphorelay between Bacillus subtilis and Bacillus anthracis revealed high homology in the phosphorelay orthologs of Spo0F, Spo0B, and Spo0A. The sensor domains of sensor histidine kinases are poorly conserved between species, making ortholog recognition tenuous. Putative sporulation sensor histidine kinases of B. anthracis were identified by homology to the HisKA domain of B. subtilis sporulation sensor histidine kinases, which interacts with Spo0F. Nine possible kinases were uncovered, and their genes were assayed for complementation of kinase mutants of B. subtilis, for ability to drive lacZ expression in B. subtilis and B. anthracis, and for the effect of deletion of each on the sporulation of B. anthracis. Five of the nine sensor histidine kinases were inferred to be capable of inducing sporulation in B. anthracis. Four of the sensor kinases could not be shown to induce sporulation; however, the genes for two of these were frameshifted in all B. anthracis strains and one of these was also frameshifted in the pathogenic pXO1-bearing Bacillus cereus strain G9241. It is proposed that acquisition of plasmid pXO1 and pathogenicity may require a dampening of sporulation regulation by mutational selection of sporulation sensor histidine kinase defects. The sporulation of B. anthracis ex vivo appears to result from any one or a combination of the sporulation sensor histidine kinases remaining.
芽孢杆菌属物种中芽孢形成的起始由磷酸化信号转导途径调控，该途径由几种组氨酸传感器激酶响应细胞和代谢信号而激活。枯草芽孢杆菌和炭疽芽孢杆菌之间磷酸化中继蛋白成分的比较显示，Spo0F、Spo0B和Spo0A的磷酸化中继直系同源物具有高度同源性。不同物种间传感器组氨酸激酶的传感器结构域保守性较差，使得直系同源物识别具有不确定性。通过与枯草芽孢杆菌芽孢形成传感器组氨酸激酶的HisKA结构域同源性鉴定了炭疽芽孢杆菌假定的芽孢形成传感器组氨酸激酶，该结构域与Spo0F相互作用。发现了9种可能的激酶，并检测了它们的基因对枯草芽孢杆菌激酶突变体的互补作用、在枯草芽孢杆菌和炭疽芽孢杆菌中驱动lacZ表达的能力以及每个基因缺失对炭疽芽孢杆菌芽孢形成的影响。9种传感器组氨酸激酶中有5种被推断能够诱导炭疽芽孢杆菌形成芽孢。4种传感器激酶未显示能诱导芽孢形成；然而，其中2种的基因在所有炭疽芽孢杆菌菌株中发生了移码突变，其中1种在携带致病质粒pXO1的蜡样芽孢杆菌菌株G9241中也发生了移码突变。有人提出，获得质粒pXO1和致病性可能需要通过对芽孢形成传感器组氨酸激酶缺陷进行突变选择来减弱芽孢形成调控。炭疽芽孢杆菌在体外的芽孢形成似乎是由剩余的任何一种或多种芽孢形成传感器组氨酸激酶导致的。
