Morimyo M, Shimazu Y
Mol Gen Genet. 1976 Sep 23;147(3):243-50. doi: 10.1007/BF00582875.
Conclusive evidence in presented to show that the gene uvrA is dispensable, but the uvrB is indispensable for an Escherichia coli strain carrying gene polA1. We constructed strains E139 (sup-126 polAl uvrB59) and E159 (sup-126 polAl uvrA43) where mutations polAl, uvrB59 and uvrA43 are amber mutations and mutation sup-126 is an amber suppressor mutation effective at 30 degrees C but not at 42 degrees C. At 42 degrees C, strain E139 is inviable but strain E159 viable whereas both are viable at 30 degrees C. Revertants of E139 viable at 42 degrees C occurred spontaneously at a frequency of about 3 X 10(-4). One of the revertants was shown to be caused by suppressor mutation, designated spu, rather than back mutation of the gene uvrB59 or polAl or amber suppressor mutation. Viabilities of the revertants varied from 10(-3) to 1.0 at 42 degrees C compared with those of 30 degrees C. At 42 degrees C, all the revertants with normal viabilities at 42 degrees C were non-filamentous in contrast to the filamentous character of E139. However, strain E159 was viable at 42 degrees C despite its filamentous character. We conclude that the gene uvrB is involved not only in excision repair but also in normal growth in a polA background.
确凿证据表明，uvrA基因对于携带polA1基因的大肠杆菌菌株而言是可有可无的，但uvrB基因却是不可或缺的。我们构建了菌株E139（sup-126 polA1 uvrB59）和E159（sup-126 polA1 uvrA43），其中polA1、uvrB59和uvrA43突变均为琥珀突变，而sup-126突变是一种琥珀抑制突变，在30℃时有效，但在42℃时无效。在42℃时，菌株E139无法存活，但菌株E159可以存活，而在30℃时两者均能存活。E139在42℃时的自发回复突变体出现频率约为3×10⁻⁴。其中一个回复突变体被证明是由抑制突变引起的，命名为spu，而非uvrB59或polA1基因的回复突变或琥珀抑制突变。与在30℃时相比，回复突变体在42℃时的存活率在10⁻³至1.0之间变化。在42℃时，所有在42℃时具有正常存活率的回复突变体均无丝状特征，这与E139的丝状特征形成对比。然而，菌株E159尽管具有丝状特征，但在42℃时仍可存活。我们得出结论，uvrB基因不仅参与切除修复，还参与polA背景下的正常生长。
