Salmonella typhimurium mutants generally defective in chemotaxis

Salmonella typhimurium mutants defective in cytidine monophosphate kinase (cmk).

Mutants of Salmonella typhimurium defective in cytidine 5'-monophosphate (CMP) kinase (cmk) have been isolated. The mutants also lack the ability to phosphorylate 2'-deoxyCMP, indicating that one enzyme is responsible for the phosphorylation of both CMP and deoxyCMP to the corresponding diphosphates. In glucose minimal medium the mutants grow at the same rate as the parental strain; however, th...

Salmonella typhimurium prfA mutants defective in release factor 1.

Mutations have been characterized that map in the prfA gene of Salmonella typhimurium. These weak amber suppressors show increased readthrough of UAG but not UAA or UGA codons. Some hemA mutants exhibit a similar suppressor activity due to transcriptional polarity on prfA. All of the suppressors mapping in prfA are recessive to the wild type. Two mutant prfA genes were cloned onto plasmids, and...

Salmonella typhimurium proline mutants.

Proline Mutants of Salmonella Typhimurium.

CCORDING to previous analyses of 16 proline-requiring mutants of SalmonA d l a typhimurium, made genetically by NIELSEN (DEMEREC et al. 1954) and biochemically by JSANAZIR (1956; DEMEREC et al. 1955), the mutants fell into at least three groups. Recently, the number of proline-requiring mutants in our collection was increased to more than 200, and useful new techniques were devised or adapted f...

Histidine Regulatory Mutants in Salmonella typhimurium

Regulation of the histidine operon in Salmonella typhimurium has been shown to involve at least six separate genes (Roth, Antdn & Hartman, 1966; Ant&, 1968). Mutations in any one of these separate genes can destroy the ability of the cell to repress fully the histidine biosynthetic enzymes. In order to understand this regulatory mechanism and the nature of these mutations, we have studied the d...