Single-stranded DNA binding proteins (SSBs) from prokaryotic transmissible plasmids.
Single-stranded DNA binding proteins (SSBs) from prokaryotic transmissible plasmids.
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来自原核可传播质粒的单链 DNA 结合蛋白 (SSB)。
DOI：
10.1002/prot.340090206
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发表时间：
1991
期刊：
影响因子：
2.9
通讯作者：
Chase,JW
中科院分区：
文献类型：
--
作者：
Ruvolo,PP;Keating,KM;Williams,KR;Chase,JW
测定了pIP 71 a、pIP 231 a和R64接合质粒编码的单链DNA结合蛋白（SSB）的DNA和蛋白质序列，并与大肠杆菌SSB和F质粒编码的SSB进行了比较。尽管所有这些蛋白质的氨基酸序列在蛋白质的NH 2-末端三分之二内高度保守，但它们在COOH-末端第三区域中分歧。许多先前被认为直接或间接参与DNA结合的氨基酸残基在所有这些SSB中是保守的。这些残基包括Trp-40、Trp-54、Trp-88、His-55和Phe-60。在这些序列比较和DNA结合研究的基础上，首次提出了Tyr-70在DNA结合中的作用。虽然这些蛋白质的COOH-末端三分之一比它们的NH 2-末端区域偏离更多，但所有五种蛋白质的COOH-末端五个氨基酸残基是相同的。此外，所有这些蛋白质都具有抗蛋白酶的特性，具有NH 2末端核心和酸性COOH末端区域。尽管质粒SSB蛋白之间具有高度的序列同源性，但F-质粒SSB似乎是唯一一个既不能很好地结合poly（dA）也不能刺激DNA聚合酶III全酶延伸速率的SSB。Poly [d（A-T）]熔解研究表明，至少有三种质粒编码的SSB是比E更好的螺旋去稳定蛋白。coliSSB蛋白。
The DNA and protein sequences of single‐stranded DNA binding proteins (SSBs) encoded by the plP71a, plP231a, and R64 conjugative plasmids have been determined and compared toEscherichia coliSSB and the SSB encoded by F‐plasmid. Although the amino acid sequences of all of these proteins are highly conserved within the NH2‐terminal two‐thirds of the protein, they diverge in the COOH‐terminal third region. A number of amino acid residues which have previously been implicated as being either directly or indirectly involved in DNA binding are conserved in all of these SSBs. These residues include Trp‐40, Trp‐54, Trp‐88, His‐55, and Phe‐60. On the basis of these sequence comparisons and DNA binding studies, a role for Tyr‐70 in DNA binding is suggested for the first time. Although the COOH‐terminal third of these proteins diverges more than their NH2‐terminal regions, the COOH‐terminal five amino acid residues of all five of these proteins are identical. In addition, all of these proteins share the characteristic property of having a protease resistant, NH2‐terminal core and an acidic COOH‐terminal region. Despite the high degree of sequence homology among the plasmid SSB proteins, the F‐plasmid SSB appears unique in that it was the only SSB tested that neither bound well to poly(dA) nor was able to stimulate DNA polymerase III holoenzyme elongation rates. Poly [d(A‐T)] melting studies suggest that at least three of the plasmid encoded SSBs are better helix‐destabilizing proteins than is theE. coliSSB protein.