Investigating the role of secA2 in secretion and glycosylation of a fimbrial adhesin in Streptococcus parasanguis FW213
Investigating the role of secA2 in secretion and glycosylation of a fimbrial adhesin in Streptococcus parasanguis FW213
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DOI：
10.1111/j.1365-2958.2004.04116.x
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发表时间：
2004-08-01
影响因子：
3.6
通讯作者：
Fives-Taylor, PM
中科院分区：
文献类型：
--
作者：
Chen, Q;Wu, H;Fives-Taylor, PM
副血链球菌 FW213（一种初级定植菌）对牙齿表面的粘附主要是由毛周长菌毛介导的。菌毛结构单元 Fap1 对于菌毛生物发生、体外牙齿模型的粘附和生物膜形成是不可或缺的。成熟的 Fap1 是一种表观分子质量为 200 kDa 的糖蛋白。从转座子突变体文库筛选的一些突变体中不存在糖基化 Fap1。转座位点的定位揭示了一个被确定为 secA2 的基因，该基因与典型的 secA 基因不同。在 FW213 中，糖基化的 Fap1 存在于包括细胞质在内的所有亚细胞部分中。在VT1574（通过框内删除产生的secA2非极性突变体）中，不分泌Fap1。糖基化的 Fap1 存在于突变体的膜和细胞质中，但数量大大减少。当 VT1574 被质粒携带的 secA2 补充时，Fap1 的分泌和丰度得以恢复。 secA2 突变的分泌缺陷似乎仅限于一小部分蛋白质，例如 Fap1 和 FimA。这些数据表明 Fap1 分泌而不是糖基化是 secA2 缺失的主要影响；然而，这种缺失也对 Fap1 丰度产生了影响。测试了另外两个删除了不同区域的 secA2 突变体分泌 Fap1 的能力。一种突变体完全无法分泌 Fap1，而另一种则能够分泌，但分泌量有所减少。这些数据表明后一个突变体中删除的区域（核苷酸 2032-2337）对于 Fap1 分泌来说是可有可无的。
Adhesion of Streptococcus parasanguis FW213, a primary colonizer, to the tooth surface is mediated mainly by peritrichous long fimbriae. The fimbrial structural unit, Fap1, is indispensable for fimbriae biogenesis, adhesion to an in vitro tooth model and biofilm formation. Mature Fap1 is a glycoprotein with an apparent molecular mass of 200 kDa. Glycosylated Fap1 is not present in some mutants screened from a transposon mutant library. Localization of the transposition sites revealed a gene determined to be secA2, which is distinct from the canonical secA gene. In FW213, glycosylated Fap1 was present in all the subcellular fractions including the cytoplasm. In VT1574, a non-polar mutant of secA2 generated by in frame deletion, Fap1 was not secreted. Glycosylated Fap1 was present in the membrane and cytoplasm of the mutant, although in greatly reduced amounts. Fap1 secretion and abundance were restored when VT1574 was complemented by a plasmid-borne secA2. The secretion defect of the secA2 mutation appears to be limited to a small group of proteins such as Fap1 and FimA. These data suggested that Fap1 secretion rather than glycosylation was the major effect of the deletion of secA2; however, this deletion also had an impact on Fap1 abundance. Two more secA2 mutants with different regions deleted were tested for their ability to secrete Fap1. One mutant was completely unable to secrete Fap1 while the other was able to secrete, but in a decreased amount. These data suggest that the region deleted in the latter mutant (nucleotides 2032-2337) is dispensable for Fap1 secretion.