Martinez-Canamero M, Munoz-Dorado J, Farez-Vidal E, Inouye M, Inouye S
Department of Biochemistry, Robert Wood Johnson Medical School, University of Medicine and Dentistry of New Jersey, Piscataway 08854.
J Bacteriol. 1993 Aug;175(15):4756-63. doi: 10.1128/jb.175.15.4756-4763.1993.
Myxococcus xanthus is a developmental gram-negative bacterium which forms multicellular fruiting bodies upon nutrient starvation. This bacterium was found to contain a 115-kDa membrane protein which separated with the inner membrane fraction by sucrose density gradient centrifugation. The gene for this protein was cloned, and its DNA sequence was determined. The deduced amino acid sequence consists of 1,061 residues. This protein contains a putative signal sequence and many short segments, found scattered throughout the entire protein, that have sequence similarities with OmpA, a major outer membrane protein of Escherichia coli. Thus, the gene was designated oar (OmpA-related protein). A second open reading frame was found 36 bases downstream of the oar termination codon. This open reading frame encodes a protein of 236 residues and contains a putative lipoprotein signal sequence. An aor disruption mutation (delta oar) showed no effect on vegetative growth but caused abnormal morphogenesis during development and reduced myxospore formation. When examined with a light microscope, delta oar cells were unable to aggregate on developmental agar, indicating that Oar is required for cellular adhesiveness during development.
黄色粘球菌是一种发育型革兰氏阴性细菌，在营养饥饿时会形成多细胞子实体。人们发现这种细菌含有一种115 kDa的膜蛋白，通过蔗糖密度梯度离心可与内膜组分分离。该蛋白的基因被克隆，并测定了其DNA序列。推导的氨基酸序列由1061个残基组成。这种蛋白包含一个假定的信号序列以及许多短片段，这些短片段散布在整个蛋白中，与大肠杆菌的主要外膜蛋白OmpA具有序列相似性。因此，该基因被命名为oar（OmpA相关蛋白）。在oar终止密码子下游36个碱基处发现了第二个开放阅读框。这个开放阅读框编码一个236个残基的蛋白，并包含一个假定的脂蛋白信号序列。一个aor缺失突变体（Δoar）对营养生长没有影响，但在发育过程中导致异常形态发生并减少了粘孢子的形成。在光学显微镜下观察时，Δoar细胞在发育琼脂上无法聚集，这表明Oar是发育过程中细胞黏附所必需的。
