An ABC Transporter Plays a Developmental Aggregation Role in Myxococcus xanthus
An ABC Transporter Plays a Developmental Aggregation Role in Myxococcus xanthus
复制标题
DOI：
10.1128/jb.180.21.5697-5703.1998
复制
发表时间：
1998-11
影响因子：
3.2
通讯作者：
M. Ward;Kenny C. Mok;D. Astling;H. Lew;D. Zusman
中科院分区：
文献类型：
--
作者：
M. Ward;Kenny C. Mok;D. Astling;H. Lew;D. Zusman
摘要黄色粘球菌是一种革兰氏阴性细菌，具有复杂的生活史。自趋化性，细胞释放一个自我产生的信号分子的过程，可能是主要的机制，促进定向运动在这两个生命周期的营养群集和发育聚集阶段。该过程需要Frz信号转导系统，包括FrzZ，一种由两个结构域组成的蛋白质，两者均显示出与肠道趋化反应调节因子CheY的同源性。FrzZ的第一个结构域（FrzZ 1），当在酵母双杂交系统中作为诱饵表达并对文库进行筛选时，显示出潜在地与编码ATP结合盒（AbcA）的蛋白质的C-末端部分相互作用。激活结构域-AbcA融合蛋白不与FrzZ的第二结构域（FrzZ 2）或与另外两个M.含有苍耳反应调节因子的蛋白质作为诱饵，表明FrzZ 1-AbcA相互作用可能是特异性的。abcA基因的上游区域的克隆和测序显示ATP结合盒被连接到一个大的疏水性的，潜在的跨膜结构域。这种域组织是执行出口功能的ABC运输机子组的特征。abc A下游的克隆和测序表明ABC转运蛋白位于含有三个开放阅读框的操纵子的起始处。abcA基因中的插入突变导致细胞显示卷曲聚集表型，提供了额外的证据表明FrzZ和AbcA可能是同一信号转导途径的一部分。abcA下游基因突变的细胞没有发育缺陷。在细胞混合实验中的建议出口商的作用AbcA的分析表明，ABC转运突变体可以通过细胞外互补获救。我们推测AbcA蛋白可能参与了自趋化过程所需的分子的输出。
ABSTRACT Myxococcus xanthus is a gram-negative bacterium which has a complex life cycle. Autochemotaxis, a process whereby cells release a self-generated signaling molecule, may be the principal mechanism facilitating directed motility in both the vegetative swarming and developmental aggregation stages of this life cycle. The process requires the Frz signal transduction system, including FrzZ, a protein which is composed of two domains, both showing homology to the enteric chemotaxis response regulator CheY. The first domain of FrzZ (FrzZ1), when expressed as bait in the yeast two-hybrid system and screened against a library, was shown to potentially interact with the C-terminal portion of a protein encoding an ATP-binding cassette (AbcA). The activation domain-AbcA fusion protein did not interact with the second domain of FrzZ (FrzZ2) or with two other M. xanthus response regulator-containing proteins presented as bait, suggesting that the FrzZ1-AbcA interaction may be specific. Cloning and sequencing of the upstream region of the abcA gene showed the ATP-binding cassette to be linked to a large hydrophobic, potentially membrane-spanning domain. This domain organization is characteristic of a subgroup of ABC transporters which perform export functions. Cloning and sequencing downstream of abcAindicated that the ABC transporter is at the start of an operon containing three open reading frames. An insertion mutation in theabcA gene resulted in cells displaying the frizzy aggregation phenotype, providing additional evidence that FrzZ and AbcA may be part of the same signal transduction pathway. Cells with mutations in genes downstream of abcA showed no developmental defects. Analysis of the proposed exporter role of AbcA in cell mixing experiments showed that the ABC transporter mutant could be rescued by extracellular complementation. We speculate that the AbcA protein may be involved in the export of a molecule required for the autochemotactic process.