P02943 (LAMB_ECOLI) Reviewed, UniProtKB/Swiss-Prot

Names and origin

Protein names

Recommended name:
Maltoporin

Alternative name(s):
Lambda receptor protein
Maltose-inducible porin

Gene names

Name:	lamB
Synonyms:	malB
Ordered Locus Names:	b4036, JW3996

Organism

Escherichia coli (strain K12)

Taxonomic identifier

83333 [NCBI]

Taxonomic lineage

Bacteria › Proteobacteria › Gammaproteobacteria › Enterobacteriales › Enterobacteriaceae › Escherichia

Protein attributes

Sequence length	446 AA.
Sequence status	Complete.
Sequence processing	The displayed sequence is further processed into a mature form.
Protein existence	Evidence at protein level

General annotation (Comments)

Function	Involved in the transport of maltose and maltodextrins, indispensable for translocation of dextrins containing more than three glucosyl moieties. A hydrophobic path ("greasy slide") of aromatic residues serves to guide and select the sugars for transport through the channel. Also acts as a receptor for several bacteriophages including lambda. HAMAP MF_01301
Subunit structure	Homotrimer formed of three 18-stranded antiparallel beta-barrels, containing three independent channels. Ref.13
Subcellular location	Cell outer membrane; Multi-pass membrane protein Ref.13.
Induction	By maltose. HAMAP MF_01301
Sequence similarities	Belongs to the porin LamB (TC 1.B.3) family. [View classification]

Ontologies

Keywords
Biological process	Ion transport Sugar transport Transport
Cellular component	Cell membrane Cell outer membrane Membrane
Domain	Signal Transmembrane Transmembrane beta strand
Molecular function	Porin
PTM	Disulfide bond
Technical term	3D-structure Complete proteome Reference proteome
Gene Ontology (GO)
Biological process	maltose transport Inferred from electronic annotation. Source: InterPro
Cellular component	cell outer membrane Inferred from electronic annotation. Source: UniProtKB-SubCell plasma membrane Inferred from electronic annotation. Source: UniProtKB-KW pore complex Inferred from electronic annotation. Source: UniProtKB-KW
Molecular function	porin activity Inferred from electronic annotation. Source: UniProtKB-KW protein binding Inferred from physical interaction. Source: IntAct sugar:hydrogen symporter activity Inferred from electronic annotation. Source: InterPro
Complete GO annotation...

Binary interactions

With	Entry	#Exp.	IntAct	Notes
secA	P10408	3	EBI-371309,EBI-543213

Sequence annotation (Features)

Feature key

Position(s)

Length

Description

Graphical view

Feature identifier

Molecule processing

Signal peptide

1 – 25

25

HAMAP MF_01301

Chain

26 – 446

421

Maltoporin HAMAP MF_01301

PRO_0000025175

Regions

Topological domain

26

1

Periplasmic Ref.10 Ref.11

Transmembrane

27 – 35

9

Beta stranded HAMAP MF_01301

Topological domain

36 – 64

29

Extracellular Ref.10 Ref.11

Transmembrane

65 – 78

14

Beta stranded HAMAP MF_01301

Topological domain

79 – 80

2

Periplasmic Ref.10 Ref.11

Transmembrane

81 – 93

13

Beta stranded HAMAP MF_01301

Topological domain

94 – 104

11

Extracellular Ref.10 Ref.11

Transmembrane

105 – 115

11

Beta stranded HAMAP MF_01301

Topological domain

116 – 122

7

Periplasmic Ref.10 Ref.11

Transmembrane

123 – 130

8

Beta stranded HAMAP MF_01301

Topological domain

131 – 148

18

Extracellular Ref.10 Ref.11

Transmembrane

149 – 159

11

Beta stranded HAMAP MF_01301

Topological domain

160 – 161

2

Periplasmic Ref.10 Ref.11

Transmembrane

162 – 173

12

Beta stranded HAMAP MF_01301

Topological domain

174 – 191

18

Extracellular Ref.10 Ref.11

Transmembrane

192 – 205

14

Beta stranded HAMAP MF_01301

Topological domain

206 – 209

4

Periplasmic Ref.10 Ref.11

Transmembrane

210 – 222

13

Beta stranded HAMAP MF_01301

Topological domain

223 – 234

12

Extracellular Ref.10 Ref.11

Transmembrane

235 – 248

14

Beta stranded HAMAP MF_01301

Topological domain

249 – 250

2

Periplasmic Ref.10 Ref.11

Transmembrane

251 – 263

13

Beta stranded HAMAP MF_01301

Topological domain

264 – 290

27

Extracellular Ref.10 Ref.11

Transmembrane

291 – 305

15

Beta stranded HAMAP MF_01301

Topological domain

306 – 307

2

Periplasmic Ref.10 Ref.11

Transmembrane

308 – 323

16

Beta stranded HAMAP MF_01301

Topological domain

324 – 326

3

Extracellular Ref.10 Ref.11

Transmembrane

327 – 341

15

Beta stranded HAMAP MF_01301

Topological domain

342 – 343

2

Periplasmic Ref.10 Ref.11

Transmembrane

344 – 359

16

Beta stranded HAMAP MF_01301

Topological domain

360 – 362

3

Extracellular Ref.10 Ref.11

Transmembrane

363 – 378

16

Beta stranded HAMAP MF_01301

Topological domain

379 – 385

7

Periplasmic Ref.10 Ref.11

Transmembrane

386 – 400

15

Beta stranded HAMAP MF_01301

Topological domain

401 – 430

30

Extracellular Ref.10 Ref.11

Transmembrane

431 – 445

15

Beta stranded HAMAP MF_01301

Topological domain

446

1

Periplasmic Ref.10 Ref.11

Sites

Site

31

1

Greasy slide, important in sugar transport

Site

66

1

Greasy slide, important in sugar transport

Site

99

1

Greasy slide, important in sugar transport

Site

143

1

Important in sugar transport

Site

252

1

Greasy slide, important in sugar transport

Site

383

1

Greasy slide, important in sugar transport

Site

445

1

Greasy slide, important in sugar transport

Amino acid modifications

Disulfide bond

47 ↔ 63

Ref.9

Experimental info

Mutagenesis

33

1

R → H: Reduces ligand affinity and pore size, no longer selective for maltodextrins. Ref.5

Mutagenesis

99

1

W → R: Decreases starch affinity, slightly increases maltose affinity. Ref.5

Mutagenesis

107

1

R → S: Decreases maltodextrin affinity, increases sucrose binding and transport. Ref.5

Mutagenesis

134

1

R → A: Considerable increase in pore size and sucrose transport, slight decrease in maltose transport; when associated with A-143. Ref.12

Mutagenesis

134

1

R → D or N: Slight increase in pore size; increase in sucrose transport and slight decrease in maltose transport; when associated with D-143 and F-146. Ref.12

Mutagenesis

143

1

Y → F: Increases affinity for starch and maltose, pore size and transport of maltohexaose. Ref.5 Ref.12

Mutagenesis

146

1

D → G: Increases affinity for large dextrins. Ref.5 Ref.12

Sequence conflict

35

1

G → GSG Ref.8

Sequence conflict

208

1

P → PDP Ref.8

Sequence conflict

381

1

S → T in AAC43130. Ref.2

Sequence conflict

385

1

R → RDP Ref.8

Secondary structure

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446

Helix Strand Turn

Details...

Beta strand

27 – 39

13

Beta strand

42 – 44

3

Beta strand

64 – 78

15

Beta strand

81 – 93

13

Beta strand

95 – 98

4

Beta strand

105 – 115

11

Beta strand

124 – 130

7

Beta strand

135 – 137

3

Helix

138 – 140

3

Beta strand

142 – 145

4

Beta strand

149 – 158

10

Beta strand

160 – 180

21

Helix

185 – 187

3

Beta strand

190 – 207

18

Beta strand

210 – 221

12

Beta strand

236 – 248

13

Beta strand

251 – 261

11

Helix

262 – 264

3

Turn

265 – 267

3

Beta strand

277 – 279

3

Beta strand

285 – 287

3

Beta strand

292 – 305

14

Turn

306 – 308

3

Beta strand

309 – 322

14

Beta strand

328 – 358

31

Turn

359 – 361

3

Beta strand

364 – 381

18

Beta strand

387 – 403

17

Turn

409 – 411

3

Turn

413 – 416

4

Beta strand

418 – 420

3

Helix

423 – 425

3

Sequences

	Sequence		Length	Mass (Da)
	P02943 [UniParc]. Last modified July 21, 1986. Version 1. Checksum: B2D4E4F120DA494E	FASTA	446	49,912
	10 20 30 40 50 60 MMITLRKLPL AVAVAAGVMS AQAMAVDFHG YARSGIGWTG SGGEQQCFQT TGAQSKYRLG 70 80 90 100 110 120 NECETYAELK LGQEVWKEGD KSFYFDTNVA YSVAQQNDWE ATDPAFREAN VQGKNLIEWL 130 140 150 160 170 180 PGSTIWAGKR FYQRHDVHMI DFYYWDISGP GAGLENIDVG FGKLSLAATR SSEAGGSSSF 190 200 210 220 230 240 ASNNIYDYTN ETANDVFDVR LAQMEINPGG TLELGVDYGR ANLRDNYRLV DGASKDGWLF 250 260 270 280 290 300 TAEHTQSVLK GFNKFVVQYA TDSMTSQGKG LSQGSGVAFD NEKFAYNINN NGHMLRILDH 310 320 330 340 350 360 GAISMGDNWD MMYVGMYQDI NWDNDNGTKW WTVGIRPMYK WTPIMSTVME IGYDNVESQR 370 380 390 400 410 420 TGDKNNQYKI TLAQQWQAGD SIWSRPAIRV FATYAKWDEK WGYDYTGNAD NNANFGKAVP 430 440 ADFNGGSFGR GDSDEWTFGA QMEIWW

References

	« Hide 'large scale' referencesShow 'large scale' references »
[1]	"Gene sequence of the lambda receptor, an outer membrane protein of E. coli K12." Clement J.M., Hofnung M. Cell 27:507-514(1981) [PubMed: 6086106] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [GENOMIC DNA]. Strain: K12.
[2]	"Analysis of the Escherichia coli genome. IV. DNA sequence of the region from 89.2 to 92.8 minutes." Blattner F.R., Burland V.D., Plunkett G. III, Sofia H.J., Daniels D.L. Nucleic Acids Res. 21:5408-5417(1993) [PubMed: 8265357] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA]. Strain: K12 / MG1655 / ATCC 47076.
[3]	"The complete genome sequence of Escherichia coli K-12." Blattner F.R., Plunkett G. III, Bloch C.A., Perna N.T., Burland V., Riley M., Collado-Vides J., Glasner J.D., Rode C.K., Mayhew G.F., Gregor J., Davis N.W., Kirkpatrick H.A., Goeden M.A., Rose D.J., Mau B., Shao Y. Science 277:1453-1474(1997) [PubMed: 9278503] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA]. Strain: K12 / MG1655 / ATCC 47076.
[4]	"Highly accurate genome sequences of Escherichia coli K-12 strains MG1655 and W3110." Hayashi K., Morooka N., Yamamoto Y., Fujita K., Isono K., Choi S., Ohtsubo E., Baba T., Wanner B.L., Mori H., Horiuchi T. Mol. Syst. Biol. 2:E1-E5(2006) [PubMed: 16738553] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA]. Strain: K12 / W3110 / ATCC 27325 / DSM 5911.
[5]	"Sequence determinants in the lamB gene of Escherichia coli influencing the binding and pore selectivity of maltoporin." Heine H.G., Kyngdon J., Ferenci T. Gene 53:287-292(1987) [PubMed: 3301537] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [GENOMIC DNA] OF 1-156, MUTAGENESIS OF ARG-33; TRP-99; ARG-107; TYR-143 AND ASP-146.
[6]	"DNA sequence encoding the signal peptide of the lambda receptor in E. coli K 12." Clement J.M., Hedgpeth J., Hofnung M., Jacob F. C. R. Hebd. Seances Acad. Sci., D, Sci. Nat. 289:1033-1036(1979) [PubMed: 161974] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [GENOMIC DNA] OF 1-35.
[7]	"DNA sequence encoding the NH2-terminal peptide involved in transport of lambda receptor, an Escherichia coli secretory protein." Hedgpeth J., Clement J.M., Marchal C., Perrin D., Hofnung M. Proc. Natl. Acad. Sci. U.S.A. 77:2621-2625(1980) [PubMed: 6446717] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [GENOMIC DNA] OF 1-35.
[8]	"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. 170:1730-1738(1988) [PubMed: 2832377] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [GENOMIC DNA] OF 26-446.
[9]	"Role of a disulfide bond in the thermal stability of the LamB protein trimer in Escherichia coli outer membrane." Luckey M., Ling R., Dose A., Malloy B. J. Biol. Chem. 266:1866-1871(1991) [PubMed: 1988451] [Abstract] Cited for: DISULFIDE BOND.
[10]	"Permissive sites and topology of an outer membrane protein with a reporter epitope." Charbit A., Ronco J., Michel V., Werts C., Hofnung M. J. Bacteriol. 173:262-275(1991) [PubMed: 1702781] [Abstract] Cited for: TOPOLOGY.
[11]	"A model of maltodextrin transport through the sugar-specific porin, LamB, based on deletion analysis." Klebba P.E., Hofnung M., Charbit A. EMBO J. 13:4670-4675(1994) [PubMed: 7925308] [Abstract] Cited for: TOPOLOGY.
[12]	"Sucrose transport through maltoporin mutants of Escherichia coli." Van Gelder P., Dutzler R., Dumas F., Koebnik R., Schirmer T. Protein Eng. 14:943-948(2001) [PubMed: 11742115] [Abstract] Cited for: MUTAGENESIS OF ARG-134; TYR-143 AND ASP-146, X-RAY CRYSTALLOGRAPHY (3.2 ANGSTROMS).
[13]	"Protein complexes of the Escherichia coli cell envelope." Stenberg F., Chovanec P., Maslen S.L., Robinson C.V., Ilag L., von Heijne G., Daley D.O. J. Biol. Chem. 280:34409-34419(2005) [PubMed: 16079137] [Abstract] Cited for: SUBUNIT, SUBCELLULAR LOCATION. Strain: BL21-DE3.
[14]	"Structural basis for sugar translocation through maltoporin channels at 3.1-A resolution." Schirmer T., Keller T.A., Wang Y.-F., Rosenbusch J.P. Science 267:512-514(1995) [PubMed: 7824948] [Abstract] Cited for: X-RAY CRYSTALLOGRAPHY (3.1 ANGSTROMS).
[15]	"Crystal structures of various maltooligosaccharides bound to maltoporin reveal a specific sugar translocation pathway." Dutzler R., Wang Y.-F., Rizkallah P., Rosenbusch J.P., Schirmer T. Structure 4:127-134(1996) [PubMed: 8805519] [Abstract] Cited for: X-RAY CRYSTALLOGRAPHY (2.6 ANGSTROMS) WITH SUGAR SUBSTRATES.
[16]	"Channel specificity: structural basis for sugar discrimination and differential flux rates in maltoporin." Wang Y.-F., Dutzler R., Rizkallah P.J., Rosenbusch J.P., Schirmer T. J. Mol. Biol. 272:56-63(1997) [PubMed: 9299337] [Abstract] Cited for: X-RAY CRYSTALLOGRAPHY (2.4 ANGSTROMS).
+	Additional computationally mapped references.

Cross-references

Sequence databases

EMBL
GenBank
DDBJ

M16643 Genomic DNA. Translation: AAA24059.1.
M26131 Genomic DNA. Translation: AAA24060.1.
V00298 Genomic DNA. Translation: CAA23575.1.
J01648 Genomic DNA. Translation: AAB59058.1.
U00006 Genomic DNA. Translation: AAC43130.1.
U00096 Genomic DNA. Translation: AAC77006.1.
AP009048 Genomic DNA. Translation: BAE78038.1.
M24997 Genomic DNA. Translation: AAC41396.1.
V00297 Genomic DNA. Translation: CAA23574.1.

PIR

QRECL. A03443.

RefSeq

NP_418460.1. NC_000913.2.

3D structure databases

PDBe
RCSB PDB
PDBj

Entry	Method	Resolution (Å)	Chain	Positions	PDBsum
1AF6	X-ray	2.40	A/B/C	26-446	[»]
1MAL	X-ray	3.10	A/B/C	26-446	[»]
1MPM	X-ray	2.60	A/B/C	26-446	[»]
1MPN	X-ray	3.20	A/B/C	26-446	[»]
1MPO	X-ray	2.80	A/B/C	26-446	[»]
1MPQ	X-ray	3.00	A/B/C	26-446	[»]

ProteinModelPortal

P02943.

SMR

P02943. Positions 26-446.

ModBase

Search...

Protein-protein interaction databases

DIP

DIP-10082N.

IntAct

P02943. 2 interactions.

Protein family/group databases

TCDB

1.B.3.1.1. sugar porin (SP) family.

Protocols and materials databases

StructuralBiologyKnowledgebase

Search...

Genome annotation databases

EnsemblBacteria

EBESCT00000004507; EBESCP00000004507; EBESCG00000003682.
EBESCT00000015678; EBESCP00000014969; EBESCG00000014738.

GeneID

948548.

GenomeReviews

Gene locus JW3996 in contig AP009048_GR.
Gene locus b4036 in contig U00096_GR.

KEGG

ecj:JW3996.
eco:b4036.

PATRIC

32123605. VBIEscCol129921_4151.

Organism-specific databases

EchoBASE

EB0523.

EcoGene

EG10528. lamB.

Phylogenomic databases

eggNOG

COG4580.

GeneTree

EBGT00050000009784.

HOGENOM

HBG309714.

OMA

NVKSQRT.

ProtClustDB

PRK09360.

Enzyme and pathway databases

BioCyc

EcoCyc:EG10528-MONOMER.

Gene expression databases

Genevestigator

P02943.

Family and domain databases

HAMAP

MF_01301. LamB.
[Tree]

InterPro

IPR023738. Maltoporin.
IPR003192. Porin_LamB.
[Graphical view]

Gene3D

G3DSA:2.40.170.10. Porin_LamB. 1 hit.

KO

K02024.

Pfam

PF02264. LamB. 1 hit.
[Graphical view]

ProDom

PD008788. Porin_LamB. 1 hit.
[Graphical view] [Entries sharing at least one domain]

ProtoNet

Search...

Entry information

Entry name

LAMB_ECOLI

Accession

Primary (citable) accession number: P02943
Secondary accession number(s): Q2M6R8

Entry history

Integrated into UniProtKB/Swiss-Prot:	July 21, 1986
Last sequence update:	July 21, 1986
Last modified:	January 25, 2012
This is version 131 of the entry and version 1 of the sequence. [Complete history]

Entry status

Reviewed (UniProtKB/Swiss-Prot)

Annotation program

Prokaryotic Protein Annotation Program