Comparative transcriptomics with a motility-deficient mutant leads to identification of a novel polysaccharide secretion system in Nostoc punctiforme
Comparative transcriptomics with a motility-deficient mutant leads to identification of a novel polysaccharide secretion system in Nostoc punctiforme
复制标题
DOI：
10.1111/mmi.12138
复制
发表时间：
2013-02-01
影响因子：
3.6
通讯作者：
Meeks, John C.
中科院分区：
文献类型：
--
作者：
Risser, Douglas D.;Meeks, John C.
许多丝状蓝藻能够通过一种未定义的机制进行滑动运动。在异囊形成的分支中，一些菌株，如Nostoc spp.和Fisherella spp.，仅作为称为原丝的特殊细丝才能运动。在这里，我们报告了斑点状褐藻中甲基接受趋化样蛋白失活的表型，称为HmpD。hmpD基因被发现对滴虫的发育、运动和多糖分泌至关重要。hmpD菌株的比较全球转录谱分析表明，hmpD对同源体发育的转录程序有深远的影响，影响了分化过程中大约一半的差异转录基因。利用这些转录组学数据，我们确定了一个基因位点，这里指定为hps，它似乎编码了一个新的多糖分泌系统。hps位点基因转录本的上调分两步进行，第二步依赖于HmpD。hpsA、hpsBCD或hpsfg的缺失导致运动和多糖分泌完全丧失，类似于hmpD的缺失。hps位点的基因在丝状蓝藻中高度保守，但在单细胞菌株中通常不存在，这意味着丝状蓝藻具有独特的共同运动机制。
Many filamentous cyanobacteria are capable of gliding motility by an undefined mechanism. Within the heterocyst-forming clades, some strains, such as the Nostoc spp. and Fisherella spp., are motile only as specialized filaments termed hormogonia. Here we report on the phenotype of inactivation of a methyl-accepting chemotaxis-like protein in Nostoc punctiforme, designated HmpD. The gene hmpD was found to be essential for hormogonium development, motility and polysaccharide secretion. Comparative global transcriptional profiling of the hmpD strain demonstrated that HmpD has a profound effect on the transcriptional programme of hormogonium development, influencing approximately half of the genes differentially transcribed during differentiation. Utilizing this transcriptomic data, we identified a gene locus, designated here as hps, that appears to encode for a novel polysaccharide secretion system. Transcripts for the genes in the hps locus are upregulated in two steps, with the second step dependent on HmpD. Deletion of hpsA, hpsBCD or hpsEFG resulted in the complete loss of motility and polysaccharide secretion, similar to deletion of hmpD. Genes in the hps locus are highly conserved in the filamentous cyanobacteria, but generally absent in unicellular strains, implying a common mechanism of motility unique to the filamentous cyanobacteria.