HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Zaharik, M. L. Articles by Kelln, R. A. Search for Related Content PubMed PubMed Citation Articles by Zaharik, M. L. Articles by Kelln, R. A. Agricola Articles by Zaharik, M. L. Articles by Kelln, R. A.

Mutations in yhiT enable utilization of exogenous pyrimidine intermediates in Salmonella enterica serovar Typhimurium

Michelle L. Zaharik^1,

Sherry S. Lamb^1,

Kristian E. Baker^1,

¹ Department of Chemistry and Biochemistry, University of Regina, Regina, Saskatchewan S4S 0A2, Canada
² Department of Biological Chemistry, Institute of Molecular Biology, University of Copenhagen, DK1307, Denmark

Correspondence
Rod A. Kelln
rod.kelln{at}uregina.ca

Mutants capable of utilizing the pyrimidine biosynthetic intermediates carbamoylaspartate and dihydroorotate for growth were derived from pyrimidine auxotrophs of Salmonella enterica serovar Typhimurium LT2. The gain-of-function phenotypes both resulted from mutations in a single gene, yhiT, the third gene of a putative four-gene operon, yhiVUTS, for which there is no homologous region in Escherichia coli. Notably, when a mutant yhiT allele was transferred to a pyrimidine-requiring E. coli strain, the transformant was then capable of using carbamoylaspartate or dihydrorotate as a pyrimidine source. The operon arrangement of the yhiVUTS genes was supported by genetic analyses and studies employing RT-PCR, coupled to the determination of the transcriptional start site using 5'-random amplification of cDNA ends (RACE). Computer-generated predictions indicated that YhiT is an integral membrane protein with 12 putative transmembrane domains typical of bacterial transport proteins. Competition experiments showed that mutant YhiT interacts with the C₄-dicarboxylates succinate and malate, as well as the amino acids aspartate and asparagine. The native function of wild-type YhiT remains undetermined, but the collective results are consistent with a role as a general transporter of C₄-dicarboxylates and other compounds with a similar basic structure.

Present address: Response Biomedical Corp., 100-8900 Glenlyon Parkway, Burnaby, BC V5J 5J8, Canada.

Present address: Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON L8N 3Z5, Canada.

Present address: Center for RNA Molecular Biology, Case Western Reserve University, Cleveland, OH 44106, USA.

||Present address: Department of Cellular and Molecular Pharmacology, University of California-San Francisco, San Francisco, CA 94143-2542, USA.