Disease relevance of lamB

• The Escherichia coli K12 lambda receptor is a multifunctional outer membrane protein whose precursor, encoded in gene lamB, is cleaved during export [1].
• Mutations at three genetic loci (termed prlA,B,C) were previously shown to specifically suppress signal sequence mutations in the lamB gene encoding the outer membrane phage lambda receptor protein of Escherichia coli (Emr, S. D., Hanley-Way, S., and Silhavy, T. J. (1981) Cell 23, 79-88) [2].
• Amplification of a region of E. coli lamB by using a primer annealing temperature of 50 degrees C selectively detected E. coli and Salmonella and Shigella spp [3].
• The DNA sequence of the promoter-distal half of lamB from Shigella sonnei 3070 has been determined and compared with the known sequence for the Escherichia coli K12 gene [4].
• A third osmoresponsive gene that was identified was lamB, which codes for an outer membrane protein for maltodextrin transport and lambda phage adsorption; its expression was reduced fourfold with increase in the osmolarity of the growth medium [5].

High impact information on lamB

• Gene lamB is followed by molA, an unidentified reading frame corresponding to a 131-amino-acid peptide with the characteristics of an exported protein [1].
• We present the DNA sequence of lamB and of the distal region that contains repetitive and palindromic sequences and could give rise to highly stable mRNA structures [1].
• One of these mutant strains contains a small (12-base pair) deletion mutation within the region of the lamB gene that codes for the NH2-terminal signal sequence [6].
• In some of these strains the induction (with maltose) of lamB-lacZ hybrid protein synthesis was lethal because of membrane damage resulting from an incomplete export of this protein to the outer membrane [7].
• Mutants in this class fail to produce the lamB-lacZ hybrid protein but retain the ability to express lacY, which is located distal to the hybrid gene [7].

Chemical compound and disease context of lamB

• The pores of the C. crescentus porins are slightly larger than those of E. coli K-12, since maltotetraose supported growth of the C. crescentus malA mutant but failed to support growth of the E. coli lamB mutant [8].
• Permeation of maltose and maltotriose through the outer membrane of the C. crescentus malA mutant was slower than permeation through the outer membrane of an E. coli lamB mutant, which suggests a low porin activity in C. crescentus [8].
• Some Escherichia coli K-12 lamB mutants, those producing reduced amounts of LamB protein (one-tenth the wild type amount), grow normally on dextrins but transport maltose when present at a concentration of 1 microM at about one-tenth the normal rate. lamB Dex- mutants were found as derivatives of these strains [9].
• Subsequently, a hybrid lamB gene carrying the sequence of the coronavirus antigen was placed downstream of the m-toluate-responsive Pm promoter of the TOL (toluene degradation) plasmid [10].

Biological context of lamB

• The lamB gene is situated in the malKlamBmalM operon, which forms a divergent operon complex together with the malEFG operon [11].
• Fifteen lamB mutations generated by hydroxylamine and linker mutagenesis, as well as spontaneous mutations, were analyzed [12].
• Gene fusion of the lamB signal sequence to the N-terminal part of the lactose permease gene resulted in production of active fused permease in the E. coli membrane [13].
• Mutations that affect lamB gene expression at a posttranscriptional level [7].
• The promoter region of ompS is highly homologous to the malK-lamB promoter of E. coli and the ompS gene is controlled by MalT in E. coli [14].

Anatomical context of lamB

• Two proteins encoded in the malB locus, the maltose-binding protein and the LamB protein, are exported to the periplasm and outer membrane, respectively [15].

Associations of lamB with chemical compounds

• Pretreatment of lamB cells for 3 h with 10 mM Tris, pH 7.2, containing 25 mM Ca++ resulted in a Ca++-induced shift of the apparent Km of the maltose transport system from about 100 microM to about 15 microM [16].
• LamB protein contributed to the ability of the bacteria to remove sugar from glucose-limited chemostats, and well-characterized lamB mutants with reduced stability constants for glucose were less growth competitive under glucose limitation than those with wild-type affinity [17].
• Site-directed mutagenesis of the lamB gene was used to introduce individual cysteine substitutions at 20 sites in two regions (surface loops L7 and L8) of LamB protein significant in antibody recognition [18].
• The gene malH is adjacent to malB and malR, which encode an EII(CB) component of the phosphoenolpyruvate-dependent sugar:phosphotransferase system and a putative regulatory protein, respectively [19].
• The authors suggest that for F. mortiferum, the products of malB and malH catalyse the phosphorylative translocation and intracellular hydrolysis of the five isomers of sucrose and of related alpha-linked glucosides [19].

Other interactions of lamB

• Sixteen signal peptides were found, including those of lamB, btuB, and malE [20].
• OmpC overexpression did not cause a significant decrease in expression of a LamB-LacZ hybrid protein produced from a lamB-lacZ fusion in which the fusion joint was at the second amino acid of the LamB signal sequence [21].
• The crystallization of outer membrane proteins from Escherichia coli. Studies on lamB and ompA gene products [22].
• This indicates that the same kind of regulatory mechanism is used to activate the ompS expression in V. cholerae and malK-lamB expression in E. coli [14].
• Base up-regulated core genes for maltodextrin transport (lamB, mal), ATP synthase (atp), and DNA repair (recA, mutL) [23].

Analytical, diagnostic and therapeutic context of lamB

• Polymerase chain reaction (PCR) amplification and gene probe detection of regions of two genes, lacZ and lamB, were tested for their abilities to detect coliform bacteria [3].
• Further sequence analysis of the phage lambda receptor site. Possible implications for the organization of the lamB protein in Escherichia coli K12 [24].

References