Disease relevance of lacY

• The nucleotide sequence of the lacY gene coding for lactose permease (M protein) in Escherichia coli has been determined [1].
• The nucleotide sequences of the Klebsiella pneumoniae lacI and lacZ genes and part of the lacY gene were determined, and these genes were located and oriented relative to one another [2].
• The effect of the lacY gene on the induction of IPTG inducible promoters, studied in Escherichia coli and Pseudomonas fluorescens [3].

High impact information on lacY

• Moreover, even when an odd number of helices is deleted, the C terminus remains on the cytoplasmic surface of the membrane, as judged by lacY-phoA fusion analysis [4].
• Stop codons (TAA) have now been substituted sequentially for amino acid codons 396-401 in the lacY gene, and the termination mutants were expressed from the plasmid pT7-5 [5].
• By using restriction fragments of lacY genes harboring specific site-directed mutations, a fusion gene has been constructed that encodes a permease in which His-35 and His-39 are replaced with arginine, and His-205 with glutamine (RQHE permease) [6].
• Arg-302, His-322, and Glu-325, neighboring residues in putative helices IX and X of the lac permease (lacY gene product) of Escherichia coli, play an important role in lactose/H+ symport, possibly as components of a catalytic triad similar to that postulated for the serine proteases [Kaback, H. R. (1987) Biochemistry 26, 2071-2076] [6].
• The lac operon of Escherichia coli spans approximately 5300 base pairs and includes the lacZ, lacY, and lacA genes in addition to the operator, promoter, and transcription termination regions [7].

Chemical compound and disease context of lacY

• An intergenic RNA segment between lacY and lacA of the lactose operon in Escherichia coli is cleaved by RNase P, an endoribonuclease [8].
• This study was carried out to determine the effect of N,N-diethyl-m-toluamide (DEET) and pyridostigmine bromide (PB), alone and in combination, on P-gp expression using Escherichia coli leaky mutant transformed with Mdr1 gene (pT5-7/mdr1), which codes for P-gp or lactose permease (pT5-7/lacY) as negative control [9].

Biological context of lacY

• Determination of lacZ and lacY mRNA levels revealed a pattern of reduction that was similar to the Lac-proteins, indicating a relation between translation inhibition and mRNA degradation as a response to antisense PNA treatment [10].
• The membrane topology of Escherichia coli lac permease was analyzed using a set of 36 lac permease-alkaline phosphatase (lacY-phoA) gene fusions [11].
• Searches of the Y. pestis genome databases revealed the presence of noncontiguous sequences highly homologous to Escherichia coli lacZ, lacY, and lacI [12].
• The lacY from Escherichia coli strains 020 and AE43 have been cloned on plasmids which were designated p020-K358T and pAE43-D237N [13].
• These lacY mutants contain amino acid substitutions changing Lys-358 to Thr or Asp-237 to Asn, respectively [13].

Associations of lacY with chemical compounds

• Coexpression of lacY gene fragments encoding the first two transmembrane domains and the remaining 10 transmembrane domains complement in the membrane and catalyze active lactose transport [Wrubel, W., Stochaj, U., et al. (1990) J. Bacteriol. 172, 5374-5381] [14].
• Imprecise excision was monitored by selecting for melibiose+ (Mel+) phenotype, which requires only a functioning lacY gene [15].
• (ii) Recombinant C. glutamicum cells bearing the lacY gene displayed an increased influx of o-nitrophenyl-beta-D-galactopyranoside, which was inhibited by N-ethylmaleimide [16].
• Although studies on DNA microarrays revealed apparent cross-regulation of gene expression between galactose and lactose metabolism in the Stock Center isolate of MG1655, this was due to the occurrence of mutations that increased lacY expression and suppressed slow growth on galactose [17].
• Sequencing of the mutant lacY gene revealed a point mutation resulting in the substitution of glycine-159 by a cysteine residue [18].

Other interactions of lacY

• Very little lacYA and lacY mRNAs were present, whereas in cells induced to steady state, there was 10 times more lacZ than lacZYA mRNA [19].

Analytical, diagnostic and therapeutic context of lacY

• The mutants were constructed by site-directed mutagenesis such that stop codons were placed at specified positions, and the altered lacY genes were expressed at a relatively low rate from plasmid pACYC184 [20].
• As judged by [35S]methionine labeling and immunoblotting, intact permease is completely absent from the membrane of cells expressing lacY fragments either individually or together [21].
• PCR was used to amplify the lacY DNA of each mutant, which was then sequenced by the Sanger method [22].

References