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3.A.1.1.1
Maltooligosaccharide porter. The 3-D structure has been reported by Oldham et al. (2007). An altering access mechanism has been suggested for the maltose transporter resulting from rigid-body rotations (Khare et al., 2009). Bordignon et al. (2010) and Schneider et al. (2012) have reviewed the extensive knowledge available on MalEFGK2, its mode of action and its regulatory interactions.  The transporter sequesters the MalT transcriptional activator at the cytoplasmic surface of the membrane in the absence of the transport substrate (Richet et al. 2012).  The crystal structures of the transporter complex MBP-MalFGK2 bound with large malto-oligosaccharide in two different conformational states have also been determined. In the pretranslocation structure, Oldham et al. 2013 found that the transmembrane subunit MalG forms two hydrogen bonds with malto-oligosaccharide at the reducing end. In the outward-facing conformation, the transmrembrane subunit MalF binds three glucosyl units from the nonreducing end. These structural features explain why large modified malto-oligosaccharides are not transported by MalFGK2 despite their high binding affinity to MBP. In the transport cycle, substrate is channeled from MBP into the transmembrane pathway with a polarity such that both MBP and MalFGK2 contribute to the overall substrate selectivity of the system (Oldham et al. 2013).  Stabilization of the semi-open MalK2 conformation by maltose-bound MBP is key to the coupling of maltose transport to ATP hydrolysis in vivo, because it facilitates the progression of the MalK dimer from the open to the semi-open conformation, from which it can proceed to hydrolyze ATP (Alvarez et al. 2015).

Accession Number:P02916
Protein Name:MalF aka B4033
Length:514
Molecular Weight:57013.00
Species:Escherichia coli [83333]
Number of TMSs:8
Location1 / Topology2 / Orientation3: Cell inner membrane1 / Multi-pass membrane protein2 / Periplasmic side3
Substrate Maltooligosaccharides, Maltose

Cross database links:

Genevestigator: P02916
EchoBASE: EB0550
EcoGene: EG10555
eggNOG: COG1175
HEGENOM: HBG429431
DIP: DIP-10142N
RefSeq: AP_004534.1    NP_418457.1   
Entrez Gene ID: 948532   
Pfam: PF00528   
BioCyc: EcoCyc:MALF-MONOMER    ECOL168927:B4033-MONOMER   
KEGG: ecj:JW3993    eco:b4033   

Gene Ontology

GO:0043190 C:ATP-binding cassette (ABC) transporter complex
GO:0016021 C:integral to membrane
GO:0005886 C:plasma membrane
GO:0015609 F:maltooligosaccharide-importing ATPase activity
GO:0015423 F:maltose-transporting ATPase activity
GO:0042956 P:maltodextrin transport
GO:0015768 P:maltose transport

References (14)

[1] “The nucleotide sequence of the gene for malF protein, an inner membrane component of the maltose transport system of Escherichia coli. Repeated DNA sequences are found in the malE-malF intercistronic region.”  Froshauer S.et.al.   6088520
[2] “Analysis of the Escherichia coli genome. IV. DNA sequence of the region from 89.2 to 92.8 minutes.”  Blattner F.R.et.al.   8265357
[3] “The complete genome sequence of Escherichia coli K-12.”  Blattner F.R.et.al.   9278503
[4] “Highly accurate genome sequences of Escherichia coli K-12 strains MG1655 and W3110.”  Hayashi K.et.al.   16738553
[5] “Sequence of gene malG in E. coli K12: homologies between integral membrane components from binding protein-dependent transport systems.”  Dassa E.et.al.   3000770
[6] “The distribution of positively charged residues in bacterial inner membrane proteins correlates with the trans-membrane topology.”  von Heijne G.et.al.   16453726
[7] “Genetic analysis of membrane protein topology by a sandwich gene fusion approach.”  Ehrmann M.et.al.   2170984
[8] “Decoding signals for membrane protein assembly using alkaline phosphatase fusions.”  McGovern K.et.al.   1915262
[9] “Subunit interactions in ABC transporters: a conserved sequence in hydrophobic membrane proteins of periplasmic permeases defines an important site of interaction with the ATPase subunits.”  Mourez M.et.al.   9214624
[10] “Unliganded maltose-binding protein triggers lactose transport in an Escherichia coli mutant with an alteration in the maltose transport system.”  Merino G.et.al.   9401026
[11] “Characterization of transmembrane domains 6, 7, and 8 of MalF by mutational analysis.”  Ehrle R.et.al.   8636026
[12] “ATP modulates subunit-subunit interactions in an ATP-binding cassette transporter (MalFGK2) determined by site-directed chemical cross-linking.”  Hunke S.et.al.   10809785
[13] “Global topology analysis of the Escherichia coli inner membrane proteome.”  Daley D.O.et.al.   15919996
[14] “Maltose/maltodextrin system of Escherichia coli: transport, metabolism, and regulation.”  Boos W.et.al.   9529892
Structure:
2R6G   3FH6   3PUV   3PUW   3PUX   3PUY   3PUZ   3PV0   3RLF   4JBW   [...more]

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FASTA formatted sequence
1:	MDVIKKKHWW QSDALKWSVL GLLGLLVGYL VVLMYAQGEY LFAITTLILS SAGLYIFANR 
61:	KAYAWRYVYP GMAGMGLFVL FPLVCTIAIA FTNYSSTNQL TFERAQEVLL DRSWQAGKTY 
121:	NFGLYPAGDE WQLALSDGET GKNYLSDAFK FGGEQKLQLK ETTAQPEGER ANLRVITQNR 
181:	QALSDITAIL PDGNKVMMSS LRQFSGTQPL YTLDGDGTLT NNQSGVKYRP NNQIGFYQSI 
241:	TADGNWGDEK LSPGYTVTTG WKNFTRVFTD EGIQKPFLAI FVWTVVFSLI TVFLTVAVGM 
301:	VLACLVQWEA LRGKAVYRVL LILPYAVPSF ISILIFKGLF NQSFGEINMM LSALFGVKPA 
361:	WFSDPTTART MLIIVNTWLG YPYMMILCMG LLKAIPDDLY EASAMDGAGP FQNFFKITLP 
421:	LLIKPLTPLM IASFAFNFNN FVLIQLLTNG GPDRLGTTTP AGYTDLLVNY TYRIAFEGGG 
481:	GQDFGLAAAI ATLIFLLVGA LAIVNLKATR MKFD