ISOLATION AND CHARACTERIZATION OF A NEW TEMPERATURE-SENSITIVE CELL-DIVISION MUTANT OF ESCHERICHIA-COLI-K-12
ISOLATION AND CHARACTERIZATION OF A NEW TEMPERATURE-SENSITIVE CELL-DIVISION MUTANT OF ESCHERICHIA-COLI-K-12
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DOI：
10.1128/jb.124.3.1502-1507.1975
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发表时间：
1975-01-01
影响因子：
3.2
通讯作者：
DEALMEIDA, DF
中科院分区：
文献类型：
--
作者：
SANTOS, D;DEALMEIDA, DF
本文报道了大肠杆菌K-12的一个新的温度敏感突变株，它能在42 ℃形成丝状体。突变体Y16在42 ℃下仍能保持生长和脱氧核糖核酸合成。所得的多核丝在42 ℃下逐渐失去其活力，但即使在温育240分钟后，当回到30 ℃时也可以恢复。恢复分隔，并迅速恢复正常生长速率。当温度从42 ℃变化到30 ℃时，在加入氯霉素的培养物中仍能恢复。本文研究了腺嘌呤和各种核苷对Y16菌株培养物的影响，并与另一株产毒突变株T44 tif-作了比较。腺嘌呤（75 μ g/ml），已知可促进菌株T44 tif-的表达，可防止Y16培养物中细丝的发育和活力的丧失。含腺嘌呤的培养物在温度变化后的分隔恢复呈现出与无腺嘌呤培养物相似的模式。腺嘌呤在42 ℃时提供的保护作用可通过加入鸟苷加胞苷（各100 μ g/ml）而逆转.因此，高浓度的腺嘌呤和核苷对菌株Y16的影响与突变体T44 tif-所观察到的相反。然而，尽管tif-1突变在限制性温度下促进原噬菌体诱导，但在42 ℃下在Y16的溶源性衍生物的培养物中的原噬菌体诱导过程中没有检测到修饰，无论是自发的还是紫外线介导的诱导。向培养基中加入1%NaCl所提供的渗透压摩尔浓度增加并不改变菌株Y16的表型特征。该突变已定位在argG和bgl之间。ftsH和argG之间存在紧密连锁，从而在E.大肠杆菌染色体，一个以前没有描述过的参与细胞分裂的区域。报道的证据表明，菌株Y16在几个方面不同于已经描述的同类菌株。
A new temperature-sensitive mutant strain of Escherichia coli K-12 which forms filaments at 42 C has been described. The mutant, Y16, maintained growth and deoxyribonucleic acid synthesis at 42 C. The resulting multinucleate filaments gradually lost their viability at 42 C but could be recovered, even after 240 min of incubation, upon return to 30 C. Septation was resumed and growth was promptly re-established at normal rates. Recovery still took place in the presence of chloramphenicol added to the culture at the time of temperature shift from 42 to 30 C. A study has been made of the effects of adenine and various nucleosides on cultures of strain Y16 as compared with another filament-forming mutant, T44 tif-. Adenine (75 mug/ml), known to promote filamentation of strain T44 tif-, prevented the development of filaments and the loss of viability in cultures of Y16. Recovery of septation after temperature shift in cultures containing adenine presented a pattern similar to that found with the adenine-less cultures. Protection afforded by adenine at 42 C could be reversed by the addition of guanosine plus cytidine (100 mug/ml each). The effects of high concentrations of adenine and nucleosides on strain Y16 thus are the reverse of those observed with mutant T44 tif-. However, whereas tif-1 mutation promotes prophage induction at restrictive temperatures, no modification could be detected in the process of prophage induction in cultures of the lambda-lysogenic derivative of Y16 at 42 C, be it spontaneous or ultraviolet-mediated induction. The osmolarity increase afforded by 1% NaCl added to the medium did not alter the phenotype characteristics of strain Y16. The mutation has been mapped between argG and bgl. A close linkage has been observed between ftsH and argG, thereby locating the new mutation near 61 min on the map of E. coli chromosome, a previously undescribed region involved in cell division. The evidence reported indicates that strain Y16 differs in several respects from the already descirbed strains of the same class.