当前位置： SCI文献检索 > JOURNAL OF BACTERIOLOGY期刊下所有文献 > hisT is part of a multigene operon in Escherichia coli K-12.

hisT is part of a multigene operon in Escherichia coli K-12.

Abstract：

:The Escherichia coli K-12 hisT gene has been cloned, and its organization and expression have been analyzed on multicopy plasmids. The hisT gene, which encodes tRNA pseudouridine synthase I (PSUI), was isolated on a Clarke-Carbon plasmid known to contain the purF gene. The presence of the hisT gene on this plasmid was suggested by its ability to restore both production of PSUI enzymatic activity and suppression of amber mutations in a hisT mutant strain. A 2.3-kilobase HindIII-ClaI restriction fragment containing the hisT gene was subcloned into plasmid pBR322, and the resulting plasmid (designated psi 300) was mapped with restriction enzymes. Complementation analysis with different kinds of hisT mutations and tRNA structural analysis confirmed that plasmid psi 300 contained the hisT structural gene. Enzyme assays showed that plasmid psi 300 overproduced PSUI activity by ca. 20-fold compared with the wild-type level. Subclones containing restriction fragments from plasmid psi 300 inserted downstream from the lac promoter established that the hisT gene is oriented from the HindIII site toward the ClaI site. Other subclones and derivatives of plasmid psi 300 containing insertion or deletion mutations were constructed and assayed for production of PSUI activity and production of proteins in minicells. These experiments showed that: (i) the proximal 1.3-kilobase HindIII-BssHII restriction fragment contains a promoter for the hisT gene and encodes a 45,000-dalton polypeptide that is not PSUI; (ii) the distal 1.0-kilobase BssHII-ClaI restriction fragment encodes the 31,000-dalton PSUI polypeptide; (iii) the 45,000-dalton polypeptide is synthesized in an approximately eightfold excess compared with PSUI; and (iv) synthesis of the two polypeptides is coupled, suggesting that the two genes are part of an operon. Insertion of mini-Mu d1 (lac Km) phage into plasmid psi 300 confirmed that the hisT gene is the downstream gene in the operon.

journal_name

J Bacteriol

journal_title

Journal of bacteriology

authors

Marvel CC,Arps PJ,Rubin BC,Kammen HO,Penhoet EE,Winkler ME

doi

10.1128/JB.161.1.60-71.1985

subject

Has Abstract

pub_date

1985-01-01 00:00:00

pages

60-71

issue

eissn

0021-9193

issn

1098-5530

journal_volume

161

pub_type

杂志文章

在线工具

hisT is part of a multigene operon in Escherichia coli K-12.