Amino acid substitution in the lactose carrier protein with the use of amber suppressors

A. M. Huang, J. I. Lee, Steven King, T. H. Wilson

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

Five lacY mutants with amber stop codons at known positions were each placed into 12 different suppressor strains. The 60 amino acid substitutions obtained in this manner were tested for growth on lactose-minimal medium plates and for transport of lactose, melibiose, and thiomethylgalactoside. Most of the amino acid substitutions in the regions of the putative loops (between transmembrane α helices) resulted in a reasonable growth rate on lactose with moderate-to-good transport activity. In one strain (glycine substituted for Trp-10), abnormal sugar recognition was found. The substitution of proline for Trp-33 (in the region of the first α helix) showed no activity, while four additional substitutions (lysine, leucine, cysteine, and glutamic acid) showed low activity. Altered sugar specificity was observed when Trp-33 was replaced by serine, glutamine, tyrosine, alanine, histidine, or phenylalanine. It is concluded that Trp-33 may be involved directly or indirectly in sugar recognition.

Original languageEnglish (US)
Pages (from-to)5436-5441
Number of pages6
JournalJournal of Bacteriology
Volume174
Issue number16
StatePublished - 1992
Externally publishedYes

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Amino Acid Substitution
Lactose
Carrier Proteins
Melibiose
Terminator Codon
Growth
Glutamine
Phenylalanine
Histidine
Proline
Leucine
Alanine
Glycine
Serine
Lysine
Cysteine
Tyrosine
Glutamic Acid

ASJC Scopus subject areas

  • Applied Microbiology and Biotechnology
  • Immunology

Cite this

Amino acid substitution in the lactose carrier protein with the use of amber suppressors. / Huang, A. M.; Lee, J. I.; King, Steven; Wilson, T. H.

In: Journal of Bacteriology, Vol. 174, No. 16, 1992, p. 5436-5441.

Research output: Contribution to journalArticle

Huang, A. M. ; Lee, J. I. ; King, Steven ; Wilson, T. H. / Amino acid substitution in the lactose carrier protein with the use of amber suppressors. In: Journal of Bacteriology. 1992 ; Vol. 174, No. 16. pp. 5436-5441.
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