Faculty of Science, Department of Genetics, Usak University, Usak, Turkey.
PLoS One. 2013;8(1):e54112. doi: 10.1371/journal.pone.0054112. Epub 2013 Jan 11.
Phylogenetic reconstruction revealed that most Actinobacterial orthologs of S. coelicolor SCO2837, encoding a metal-dependent galactose oxidase-like protein, are found within Streptomyces and were probably acquired by horizontal gene transfer from fungi. Disruption of SCO2837 (glxA) caused a conditional bld phenotype that could not be reversed by extracellular complementation. Studies aimed at characterising the regulation of expression of glxA showed that it is not a target for other bld genes. We provide evidence that glxA is required for osmotic adaptation, although independently from the known osmotic stress response element SigB. glxA has been predicted to be part of an operon with the transcription unit comprising the upstream cslA gene and glxA. However, both phenotypic and expression studies indicate that it is also expressed from an independent promoter region internal to cslA. GlxA displays an in situ localisation pattern similar to that one observed for CslA at hyphal tips, but localisation of the former is independent of the latter. The functional role of GlxA in relation to CslA is discussed.
系统发育重建表明，链霉菌 SCO2837 中编码金属依赖型半乳糖氧化酶样蛋白的大多数放线菌直系同源物都存在于链霉菌中，可能是通过水平基因转移从真菌中获得的。SCO2837（glxA）的破坏导致条件性 bld 表型，不能通过细胞外补体来逆转。旨在表征 glxA 表达调控的研究表明，它不是其他 bld 基因的靶标。我们提供的证据表明，glxA 是渗透压适应所必需的，尽管与已知的渗透压应激反应元件 SigB 无关。glxA 被预测为与转录单元包含上游 cslA 基因和 glxA 的操纵子的一部分。然而，表型和表达研究都表明，它也可以从 cslA 内部的独立启动子区域表达。GlxA 显示出与在菌丝尖端观察到的 CslA 相似的原位定位模式，但前者的定位不依赖于后者。讨论了 GlxA 与 CslA 相关的功能作用。
