An Extracytoplasmic Function Sigma Factor Controls Cellulose Utilization by Regulating the Expression of an Outer Membrane Protein in Cytophaga hutchinsonii
An Extracytoplasmic Function Sigma Factor Controls Cellulose Utilization by Regulating the Expression of an Outer Membrane Protein in Cytophaga hutchinsonii
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胞质外功能 Sigma 因子通过调节哈钦森噬细胞外膜蛋白的表达来控制纤维素利用
DOI：
10.1128/aem.02606-18
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发表时间：
2019
影响因子：
4.4
通讯作者：
Liu Weifeng
中科院分区：
文献类型：
--
作者：
Wang Xia;Zhang Weixin;Zhou Hong;Chen Guanjun;Liu Weifeng
常见的纤维素分解细菌Cytophaga hutchinsonii使用一种独特但知之甚少的策略来利用纤维素。在纤维素生物质分解的整个过程中，外膜蛋白被认为起着关键作用;这由CHU_1276证明，它是利用纤维素所必需的。然而，其表达的调控机制尚不清楚。我们发现并鉴定了一个胞质外功能σ因子，它参与协调C. hutchinsonii通过直接调控CHU_1276的表达。本研究有助于我们理解C. hutchinsonii以调整其遗传程序，从而处理新的环境线索。摘要常见的土壤纤维素分解细菌Cytophaga hutchinsonii利用一种独特但知之甚少的策略来利用纤维素。虽然有几个基因已被确定为是纤维素利用的活性部分，但C。hutchinsonii（i）感知其环境和（ii）调节这些基因的表达这两个方面都是未知的。在这项研究中，我们确定并表征了编码细胞质外功能（ECF）σ因子（σ cell 1）的基因CHU_3097，该因子的破坏会损害C. Hutchinsonii纤维素同化作用。在体外共纯化了σ cel1及其推定的配偶体抗σ cel1（由CHU_3097下游的CHU_3096基因编码）。当细胞在葡萄糖上培养时，发现σ细胞1与内膜结合，但在纤维素的作用下，σ细胞1部分从膜上释放。当抗σ细胞1不存在时，发现这种释放发生在葡萄糖上。转录组分析发现了一个σ cell 1调节的纤维素反应基因调节子，其中编码纤维素利用所必需的基因CHU_1276的外膜蛋白被发现被CHU_3097破坏显著下调。CHU_1276的表达几乎完全恢复了CHU_3097突变体的纤维素利用，表明CHU_1276代表了σ cell 1的关键调控靶标。通过这种方式，我们的研究为ECF σ因子在协调C.哈钦森氏菌常见的纤维素分解细菌Cytophaga hutchinsonii使用一种独特但知之甚少的策略来利用纤维素。在纤维素生物质分解的整个过程中，外膜蛋白被认为起着关键作用;这由CHU_1276证明，它是利用纤维素所必需的。然而，其表达的调控机制尚不清楚。我们发现并鉴定了一个胞质外功能σ因子，它参与协调C. hutchinsonii通过直接调控CHU_1276的表达。本研究有助于我们理解C. hutchinsonii以调整其遗传程序，从而处理新的环境线索。
The common cellulolytic bacterium Cytophaga hutchinsonii uses a unique but poorly understood strategy in order to make use of cellulose. Throughout the process of cellulosic biomass breakdown, outer membrane proteins are thought to play key roles; this is evidenced by CHU_1276, which is required for the utilization of cellulose. However, the regulatory mechanism of its expression is not yet known. We found and characterized an extracytoplasmic function σ factor that is involved in coordinating the cellulolytic response of C. hutchinsonii by directly regulating the expression of CHU_1276. This study makes a contribution to our understanding of the regulatory mechanism used by C. hutchinsonii in order to adjust its genetic programs and so deal with novel environmental cues. ABSTRACT The common soil cellulolytic bacterium known as Cytophaga hutchinsonii makes use of a unique but poorly understood strategy in order to utilize cellulose. While several genes have been identified as being an active part of the utilization of cellulose, the mechanism(s) by which C. hutchinsonii both (i) senses its environment and (ii) regulates the expression of those genes are not as yet known. In this study, we identified and characterized the gene CHU_3097 encoding an extracytoplasmic function (ECF) σ factor (σcel1), the disruption of which compromised C. hutchinsonii cellulose assimilation to a large degree. The σcel1 and its putative partner anti-σcel1, encoded by the CHU_3096 gene found immediately downstream from CHU_3097, copurified in vitro. The σcel1 was discovered to be associated with inner membrane when cells were cultured on glucose and yet was partially released from the membrane in response to cellulose. This release was found to occur on glucose when the anti-σcel1 was absent. Transcriptome analyses found a σcel1-regulated, cellulose-responsive gene regulon, within which an outer membrane protein encoding the gene CHU_1276, essential for cellulose utilization, was discovered to be significantly downregulated by CHU_3097 disruption. The expression of CHU_1276 almost fully restored cellulose utilization to the CHU_3097 mutant, demonstrating that CHU_1276 represents a critical regulatory target of σcel1. In this way, our study provided insights into the role of an ECF σ factor in coordinating the cellulolytic response of C. hutchinsonii. IMPORTANCE The common cellulolytic bacterium Cytophaga hutchinsonii uses a unique but poorly understood strategy in order to make use of cellulose. Throughout the process of cellulosic biomass breakdown, outer membrane proteins are thought to play key roles; this is evidenced by CHU_1276, which is required for the utilization of cellulose. However, the regulatory mechanism of its expression is not yet known. We found and characterized an extracytoplasmic function σ factor that is involved in coordinating the cellulolytic response of C. hutchinsonii by directly regulating the expression of CHU_1276. This study makes a contribution to our understanding of the regulatory mechanism used by C. hutchinsonii in order to adjust its genetic programs and so deal with novel environmental cues.