Comparative biochemistry and genetic analysis of nucleoside hydrolase in Escherichia coli, Pseudomonas aeruginosa, and Pseudomonas fluorescens.

The pyrimidine salvage enzyme, nucleoside hydrolase, is catalyzes the irreversible hydrolysis of nucleosides into the free nucleic acid base and D-ribose. Nucleoside hydrolases have varying degrees of specificity towards purine and pyrimidine nucleosides. In E. coli, three genes were found that encode homologues of several known nucleoside hydrolases in protozoa. All three genes (designated yaaF, yeiK, and ybeK) were amplified by PCR and cloned. Two of the gene products (yeiK and ybeK) encode pyrimidine-specific nucleoside hydrolases, while the third (yaaF) encodes a nonspecific nucleoside hydrolase. All three were expressed at low levels and had different modes of regulation. As a comparative analysis, the homologous genes of Pseudomonas aeruginosa and P. fluorescens (designated nuh) were cloned. Both were determined to encode nonspecific nucleoside hydrolases. The nucleoside hydrolases of the pseudomonads exhibited markedly different modes of regulation. Both have unique promoter structures and genetic organization. Furthermore, both pseudomonad nucleoside hydrolase were found to contain an N-terminal extension of 30-35 amino acids that is shown to act as a periplasmic-signaling sequence. These are the first two nucleoside hydrolases, to date,that have been conclusively demonstrated to be exported to the periplasmic space. The physiological relevance of this is explained.

Grantor dc:publisher

University of North Texas

Year dc:date

2002

Author dc:creator

• Fields, Christopher J.

Contributors dc:contributor

• O'Donovan, Gerard A.
• Benjamin, Robert C.
• Farinha, Mark A.
• Knesek, John
• Shanley, Mark S.

• Pyrimidine nucleotides -- Metabolism.
• Hydrolases.
• Escherichia coli.
• Pseudomonas aeruginosa.
• Pseudomonas fluorescens.
• comparative biochemistry
• genetic analysis
• pyrimidine metabolism
• dihydroorotase
• nucleoside hydrolase

Statement dc:rights

• Public
• Copyright
• Fields, Christopher J.
• Copyright is held by the author, unless otherwise noted. All rights reserved.

Language dc:language

English

Identifier

oclc: 52043148
https://digital.library.unt.edu/ark:/67531/metadc3290/
ark: ark:/67531/metadc3290

OAI identifier oai:identifier

info:ark/67531/metadc3290