Tintut Y, Gralla J D
Department of Chemistry and Biochemistry, University of California, Los Angeles 90095, USA.
J Bacteriol. 1995 Oct;177(20):5818-25. doi: 10.1128/jb.177.20.5818-5825.1995.
Sigma 54 is a minor bacterial sigma factor that is not a member of the sigma 70 family of proteins but binds the same core RNA polymerase. Previously, we identified a region of sigma 54 that is important for binding core polymerase. In this work, PCR mutagenesis was used to identify specific amino acids important for this binding. The results show that important residues are clustered most closely in a short sequence that was previously speculated to be potentially homologous to a sequence in sigma 70. The mutagenesis also identifies important residues in the flanking hydrophobic-acidic region of sigma 54, which is absent in sigma 70. Overall, the data indicate that sigma 54 binds core polymerase through a sequence homologous to that of sigma 70 but in addition uses unique motifs to modify this interaction.
σ54是一种次要的细菌σ因子，它不是σ70蛋白家族的成员，但能结合相同的核心RNA聚合酶。此前，我们鉴定出σ54中对结合核心聚合酶很重要的一个区域。在这项研究中，利用PCR诱变来鉴定对这种结合很重要的特定氨基酸。结果表明，重要残基最紧密地聚集在一个短序列中，该序列此前被推测可能与σ70中的一个序列同源。诱变还鉴定出了σ54侧翼疏水-酸性区域中的重要残基，这一区域在σ70中不存在。总体而言，数据表明σ54通过与σ70同源的序列结合核心聚合酶，但此外还利用独特的基序来修饰这种相互作用。
