Genes and gene products involved in the synthesis of F-pili.
Genes and gene products involved in the synthesis of F-pili.
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参与 F-菌毛合成的基因和基因产物。
DOI：
10.1007/978-1-4613-2447-8_38
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发表时间：
1985
期刊：
影响因子：
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通讯作者：
Ippen-Ihler,K
中科院分区：
文献类型：
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作者：
Laine,S;Moore,D;Kathir,P;Ippen-Ihler,K
为了研究F-菌毛蛋白亚基的合成途径和参与F-菌毛合成的基因产物，对含有由FlacandFlac突变体菌株或在此类菌株中表达的λtra转导噬菌体合成的[35-S]蛋氨酸标记蛋白的膜级分进行了分析。我们的数据表明，除了F-pilin结构基因traA之外，成熟F-pilin亚基的合成还需要至少2个traoperon基因的表达。在缺乏这些活性的情况下，traA表达主要导致多肽Apl4的合成，其表观分子量约为14,000。我们假设该多肽对应于thetraAgene的直接产物。在traQ活性存在的情况下，traA的主要可检测产物是多肽Ap7(Q)，其以7,000的表观分子量迁移，这表明traQ产物可以加工或协助Apl4的加工。然而，多肽Ap7(Q)不是成熟的F-菌毛蛋白，因为它与抗F-菌毛血清的反应很差。似乎与F-菌毛蛋白在抗原上等同的多肽的合成，并且我们假设其需要F-菌毛蛋白N-末端的修饰，被检测为多肽Ap7*的合成。该蛋白质在我们的聚丙烯酰胺凝胶上的迁移速度比 Ap7(Q) 稍慢。多肽 Ap7* 可以用 F-菌毛抗血清有效沉淀，并且可以在 F-菌毛组装发生的条件下在内膜和外膜部分中检测到。这些数据表明 Ap7* 是成熟的 F-菌毛蛋白亚基，由内膜库组装而成。 Ap7* 的合成似乎需要traG 活性，但也可能依赖于额外的traG 活性。
Membrane fractions containing [35-S]methionine labeled proteins synthesized byFlacandFlac tramutant strains or by λtratransducing phages expressed in such strains have been analyzed in order to investigate the pathway for synthesis of the F-pilin subunit and the gene products involved in synthesis of F-pili. Our data indicate that the synthesis of a mature F-pilin subunit requires the expression of at least 2traoperon genes in addition to the structural gene for F-pilin,traA. In the absence of these activities,traAexpression results primarily in the synthesis of a polypeptide, Apl4, with an apparent molecular weight of approximately 14,000. We assume this polypeptide corresponds to the direct product of thetraAgene. In the presence oftraQactivity, the major detectable product of traA is a polypeptide, Ap7(Q), which migrates with an apparent molecular weight of 7,000, suggesting that traQ product may process or assist in the processing of Apl4. Polypeptide Ap7(Q) is not, however, mature F-pilin, since it reacts poorly with anti-F-pilus-serum. Synthesis of a polypeptide which appears to be anti-genically equivalent to F-pilin and which we assume requires a modification of the F-pilin N-terminus, is detected as synthesis of a polypeptide, Ap7*. This protein migrates slightly more slowly than Ap7(Q) on our polyacrylamide gels. Polypeptide Ap7*, can be effici¬ently precipitated with F-pilus antiserum, and can be detected in both inner membrane and outer membrane fractions under conditions where assembly of F-pili can occur. These data suggest that Ap7* is the mature F-pilin subunit and is assembled from an inner membrane pool. Synthesis of Ap7* appears to requiretraGactivity, but may also be dependent upon additionaltraactivities.