PROPHAGE INDUCTION AND CELL-DIVISION IN ESCHERICHIA-COLI .3. MUTATIONS SFIA AND SFIB RESTORE DIVISION IN TIF AND LON STRAINS AND PERMIT EXPRESSION OF MUTATOR PROPERTIES OF TIF
PROPHAGE INDUCTION AND CELL-DIVISION IN ESCHERICHIA-COLI .3. MUTATIONS SFIA AND SFIB RESTORE DIVISION IN TIF AND LON STRAINS AND PERMIT EXPRESSION OF MUTATOR PROPERTIES OF TIF
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DOI：
10.1007/bf00267322
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发表时间：
1975-01-01
期刊：
影响因子：
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通讯作者：
BUTTIN, G
中科院分区：
文献类型：
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作者：
GEORGE, J;CASTELLAZZI, M;BUTTIN, G
九个人。突变后促进细胞丝状化的噬菌体λ的原噬菌体诱导和修复不受影响。从atif双突变体中分离到恢复了41°分裂能力的“回复株”，其中大多数(95%)在紫外线(UV)照射后也失去了Lon丝状表型。从这些95%的回复突变体中：(1)94%的回复突变体在整个Tif表型中被抑制，从它们的高紫外线敏感度判断，额外的突变使它们的DNA修复能力不足；一些已被鉴定为recA突变体。(2)1%的人在41°或紫外线照射后通过次级突变恢复了对细胞分裂的控制，这些突变既不改变tifandLonm的其他表型属性，也不改变细胞的修复和重组能力：尤其是，这类“逆转株”在溶原化后仍然是热诱导的；专门抑制丝状形成的突变被定位在两个基因座上，sfiA和sfiB，分别与pyrDandleu可共转导。在其余5%的仍表现出紫外线诱导的丝状生长的回复菌株中，3%可被初步归类为真正的f+回复菌株；2%的回复菌株表现为热依赖回复菌株，仅在41°时表现出抑制Tif(和Lon)表型：2在这类菌株中已鉴定出recAts。在这些条件下，tif表达突变体的性质，这可以在这个背景下方便地分析。tif、基因和突变的作用被初步解释为基于与DNA修复相关的细胞分裂的负控制。
InE. coliK12, cell filamentation promoted bytifis enhanced by thelonmutation; in contrast, prophage induction and repair of UV-irradiated phage λ, also promoted bytif, are not affected bylon. From atif londouble mutant, “revertants” having recovered the ability to divide at 41° were isolated, among which most (95%) had also lost their Lon filamentous phenotype after ultraviolet (UV) irradiation. From these 95% of revertants: (1) 94% are suppressed for the whole Tif phenotype, by additional mutations that render them deficient in DNA repair, as judged from their high UV sensitivity; some have been characterized asrecAmutants. (2) 1% have recovered a control on cell division at 41° or after UV irradiation by means of secondary mutations altering neither the other phenotypic properties oftifandlonm nor the repair and recombination ability of the cells: in particular, this class of “revertants” remains thermoinducible upon lysogenisation; the mutations which specifically suppressfilamentation have been mapped at two loci,sfiAandsfiB, cotransducible respectively withpyrDandleu. In the remaining 5% of revertants that still exhibit an UV-induced filamentous growth, 3% can be tentatively classified as truetif+revertants; 2% behave astif thermodependentrevertants, showing suppression of the Tif (and Lon) phenotype only at 41°:2recAts have been identified in this class.Non-lysogenictif lon sfiandtif sfistrains remain viable during prolonged growth at 41°. Under these conditions,tifexpresses mutator properties, which can be conveniently analyzed in thissfibackground.The action oftif, lonandsfimutations is tentatively interpreted on the basis of a negative control of cell division specifically associated with DNA repair.