Department of Molecular Microbiology, John Innes Centre, Norwich, United Kingdom.
Department of Biochemistry and Metabolism, John Innes Centre, Norwich, United Kingdom.
J Bacteriol. 2023 Jun 27;205(6):e0013523. doi: 10.1128/jb.00135-23. Epub 2023 May 30.
In , the Bld (Bald) regulators control formation of the reproductive aerial hyphae. The functions of some of these regulators have been well characterized, but BldB has remained enigmatic. In addition to the gene itself, Streptomyces venezuelae has 10 paralogs of that sit next to paralogs of and . Transcriptome sequencing (RNA-seq) revealed that loss of BldB function causes the dramatic transcriptional upregulation of the paralogs and a novel inhibitor of sporulation, , and that cooverexpression of just two of these genes, and , was sufficient to recapitulate the mutant phenotype. Further RNA-seq analysis showed that the transcription factor WhiJ9 is required for the activation of seen in the mutant, and biochemical studies showed that WhiJ9 mediates the activation of expression by binding to direct repeats in the intergenic region. BldB and BldB9 hetero-oligomerize, providing a potential link between BldB and the locus. This work greatly expands our overall understanding of the global effects of the BldB developmental regulator. To reproduce and disperse, the filamentous bacterium develops specialized reproductive structures called aerial hyphae. The formation of these structures is controlled by the (bald) genes, many of which encode transcription factors whose functions have been characterized. An exception is BldB, a protein whose biochemical function is unknown. In this study, we gain insight into the global effects of BldB function by examining the genome-wide transcriptional effects of deleting . We identify a small set of genes that are dramatically upregulated in the absence of BldB. We show that their overexpression causes the phenotype and characterize a transcription factor that mediates the upregulation of one of these target genes. Our results provide new insight into how BldB influences development.
在放线菌中，Bld（秃发）调控因子控制着生殖气生菌丝的形成。其中一些调控因子的功能已经得到很好的描述，但 BldB 仍然是一个谜。除了本身的基因外，委内瑞拉链霉菌还拥有 10 个与 和 并列的 基因的旁系同源物。转录组测序（RNA-seq）显示，BldB 功能的丧失导致 旁系同源物的转录水平显著上调，并产生一种新的孢子形成抑制剂 ，同时，仅仅两个这些基因（ 和 ）的共过表达就足以重现 突变体的表型。进一步的 RNA-seq 分析表明，转录因子 WhiJ9 是 突变体中 激活所必需的，生化研究表明 WhiJ9 通过结合 基因间区的直接重复序列来介导 表达的激活。BldB 和 BldB9 异源寡聚化，为 BldB 和 基因座之间提供了潜在的联系。这项工作极大地扩展了我们对 BldB 发育调控因子的全局影响的整体理解。为了繁殖和扩散，丝状细菌 发育出专门的生殖结构，称为气生菌丝。这些结构的形成受 （秃发）基因控制，其中许多基因编码的转录因子的功能已经得到了描述。BldB 是一个例外，它的生化功能尚不清楚。在这项研究中，我们通过研究缺失 对全基因组转录的影响，深入了解了 BldB 功能的全局影响。我们确定了一组在缺乏 BldB 时显著上调的基因。我们表明，它们的过表达会导致 表型，并对介导其中一个靶基因上调的转录因子进行了表征。我们的研究结果为 BldB 如何影响 发育提供了新的见解。
