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Gene Review

lamB  -  maltose outer membrane porin (maltoporin)

Escherichia coli str. K-12 substr. MG1655

Synonyms: ECK4028, JW3996, malB, malL
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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


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


  1. Gene sequence of the lambda receptor, an outer membrane protein of E. coli K12. Clément, J.M., Hofnung, M. Cell (1981) [Pubmed]
  2. Localization and processing of outer membrane and periplasmic proteins in Escherichia coli strains harboring export-specific suppressor mutations. Emr, S.D., Bassford, P.J. J. Biol. Chem. (1982) [Pubmed]
  3. Detection of coliform bacteria in water by polymerase chain reaction and gene probes. Bej, A.K., Steffan, R.J., DiCesare, J., Haff, L., Atlas, R.M. Appl. Environ. Microbiol. (1990) [Pubmed]
  4. Sequence of amino acids in lamB responsible for spontaneous ejection of bacteriophage lambda DNA. Roessner, C.A., Ihler, G.M. J. Mol. Biol. (1987) [Pubmed]
  5. Identification of osmoresponsive genes in Escherichia coli: evidence for participation of potassium and proline transport systems in osmoregulation. Gowrishankar, J. J. Bacteriol. (1985) [Pubmed]
  6. Importance of secondary structure in the signal sequence for protein secretion. Emr, S.D., Silhavy, T.J. Proc. Natl. Acad. Sci. U.S.A. (1983) [Pubmed]
  7. Mutations that affect lamB gene expression at a posttranscriptional level. Schwartz, M., Roa, M., Débarbouillé, M. Proc. Natl. Acad. Sci. U.S.A. (1981) [Pubmed]
  8. ExbBD-dependent transport of maltodextrins through the novel MalA protein across the outer membrane of Caulobacter crescentus. Neugebauer, H., Herrmann, C., Kammer, W., Schwarz, G., Nordheim, A., Braun, V. J. Bacteriol. (2005) [Pubmed]
  9. Mutations that alter the transport function of the LamB protein in Escherichia coli. Wandersman, C., Schwartz, M. J. Bacteriol. (1982) [Pubmed]
  10. Nondisruptive detection of activity of catabolic promoters of Pseudomonas putida with an antigenic surface reporter system. Cebolla, A., Guzmán, C., de Lorenzo, V. Appl. Environ. Microbiol. (1996) [Pubmed]
  11. H-NS and StpA proteins stimulate expression of the maltose regulon in Escherichia coli. Johansson, J., Dagberg, B., Richet, E., Uhlin, B.E. J. Bacteriol. (1998) [Pubmed]
  12. Genetic analysis of sequences in maltoporin that contribute to binding domains and pore structure. Heine, H.G., Francis, G., Lee, K.S., Ferenci, T. J. Bacteriol. (1988) [Pubmed]
  13. Membrane assembly of lactose permease of Escherichia coli. Yamato, I. J. Biochem. (1992) [Pubmed]
  14. The ompS gene of Vibrio cholerae encodes a growth-phase-dependent maltoporin. Lång, H., Palva, E.T. Mol. Microbiol. (1993) [Pubmed]
  15. Studies on the export of the maltose-binding protein and the LamB protein. Josefsson, L.G., Hardy, S., Harayama, S., Randall, L. Ann. Microbiol. (Paris) (1982) [Pubmed]
  16. Reconstitution of maltose transport in malB and malA mutants of Escherichia coli. Brass, J.M. Ann. Microbiol. (Paris) (1982) [Pubmed]
  17. Derepression of LamB protein facilitates outer membrane permeation of carbohydrates into Escherichia coli under conditions of nutrient stress. Death, A., Notley, L., Ferenci, T. J. Bacteriol. (1993) [Pubmed]
  18. Epitope mapping by cysteine mutagenesis: identification of residues involved in recognition by three monoclonal antibodies directed against LamB glycoporin in the outer membrane of Escherichia coli. Notley, L., Hillier, C., Ferenci, T. FEMS Microbiol. Lett. (1994) [Pubmed]
  19. Metabolism of sucrose and its five isomers by Fusobacterium mortiferum. Pikis, A., Immel, S., Robrish, S.A., Thompson, J. Microbiology (Reading, Engl.) (2002) [Pubmed]
  20. Analysis of the Escherichia coli genome. IV. DNA sequence of the region from 89.2 to 92.8 minutes. Blattner, F.R., Burland, V., Plunkett, G., Sofia, H.J., Daniels, D.L. Nucleic Acids Res. (1993) [Pubmed]
  21. Translational control of exported proteins that results from OmpC porin overexpression. Click, E.M., McDonald, G.A., Schnaitman, C.A. J. Bacteriol. (1988) [Pubmed]
  22. The crystallization of outer membrane proteins from Escherichia coli. Studies on lamB and ompA gene products. Garavito, R.M., Hinz, U., Neuhaus, J.M. J. Biol. Chem. (1984) [Pubmed]
  23. Oxygen limitation modulates pH regulation of catabolism and hydrogenases, multidrug transporters, and envelope composition in Escherichia coli K-12. Hayes, E.T., Wilks, J.C., Sanfilippo, P., Yohannes, E., Tate, D.P., Jones, B.D., Radmacher, M.D., BonDurant, S.S., Slonczewski, J.L. BMC Microbiol. (2006) [Pubmed]
  24. Further sequence analysis of the phage lambda receptor site. Possible implications for the organization of the lamB protein in Escherichia coli K12. Charbit, A., Clement, J.M., Hofnung, M. J. Mol. Biol. (1984) [Pubmed]
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