Structure-Function Study of MalF Protein by Random Mutagenesis

Tapia, María I.; Mourez, Michaël; Hofnung, Maurice; Dassa, Elie

doi:10.1128/jb.181.7.2267-2272.1999

Cited by 22 publications

(9 citation statements)

References 31 publications

(29 reference statements)

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“…The MalF Ec is a member of the CUT1 (carbohydrate uptake) family [ 28 ] and is one of the most extensively studied membrane permeases [ 29 ]. Unlike other membrane permeases, MalF Ec is unusual in that it consists of eight transmembrane helices instead of six and has a large periplasmic domain of 180 amino acids between transmembrane helices 3 and 4 (Fig.…”

Section: Resultsmentioning

confidence: 99%

Evolution of mal ABC transporter operons in the Thermococcales and Thermotogales

et al. 2008

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BackgroundThe mal genes that encode maltose transporters have undergone extensive lateral transfer among ancestors of the archaea Thermococcus litoralis and Pyrococcus furiosus. Bacterial hyperthermophiles of the order Thermotogales live among these archaea and so may have shared in these transfers. The genome sequence of Thermotoga maritima bears evidence of extensive acquisition of archaeal genes, so its ancestors clearly had the capacity to do so. We examined deep phylogenetic relationships among the mal genes of these hyperthermophiles and their close relatives to look for evidence of shared ancestry.ResultsWe demonstrate that the two maltose ATP binding cassette (ABC) transporter operons now found in Tc. litoralis and P. furiosus (termed mal and mdx genes, respectively) are not closely related to one another. The Tc. litoralis and P. furiosus mal genes are most closely related to bacterial mal genes while their respective mdx genes are archaeal. The genes of the two mal operons in Tt. maritima are not related to genes in either of these archaeal operons. They are highly similar to one another and belong to a phylogenetic lineage that includes mal genes from the enteric bacteria. A unique domain of the enteric MalF membrane spanning proteins found also in these Thermotogales MalF homologs supports their relatively close relationship with these enteric proteins. Analyses of genome sequence data from other Thermotogales species, Fervidobacterium nodosum, Thermosipho melanesiensis, Thermotoga petrophila, Thermotoga lettingae, and Thermotoga neapolitana, revealed a third apparent mal operon, absent from the published genome sequence of Tt. maritima strain MSB8. This third operon, mal3, is more closely related to the Thermococcales' bacteria-derived mal genes than are mal1 and mal2. F. nodosum, Ts. melanesiensis, and Tt. lettingae have only one of the mal1-mal2 paralogs. The mal2 operon from an unknown species of Thermotoga appears to have been horizontally acquired by a Thermotoga species that had only mal1.ConclusionThese data demonstrate that the Tc. litoralis and P. furiosus mdx maltodextrin transporter operons arose in the Archaea while their mal maltose transporter operons arose in a bacterial lineage, but not the same lineage as the two maltose transporter operons found in the published Tt. maritima genome sequence. These Tt. maritima maltose transporters are phylogenetically and structurally similar to those found in enteric bacteria and the mal2 operon was horizontally transferred within the Thermotoga lineage. Other Thermotogales species have a third mal operon that is more closely related to the bacterial Thermococcales mal operons, but the data do not support a recent horizontal sharing of that operon between these groups.

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Section: Resultsmentioning

confidence: 99%

Evolution of mal ABC transporter operons in the Thermococcales and Thermotogales

et al. 2008

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“…The unusually large P2 loop of MalF is of particular interest, as it is not conserved in evolution but seems to be confined to MalF proteins from enterobacteria (Ehrmann et al, 1998). Nonetheless, insertions/deletions in MalF-P2 are mostly not tolerated with respect to transport function because they were found to affect MalK localization to the membrane (Tapia et al, 1999). In contrast, MalG-P78 is part of a proline-rich sequence motif (see Fig.…”

Section: Discussionmentioning

confidence: 99%

Maltose binding protein (MalE) interacts with periplasmic loops P2 and P1 respectively of the MalFG subunits of the maltose ATP binding cassette transporter (MalFGK₂) from Escherichia coli/Salmonella during the transport cycle

Daus

Berendt

Wuttge

et al. 2007

Molecular Microbiology

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SummaryThe ATP binding cassette (ABC-) transporter mediating the uptake of maltose/maltodextrins in Escherichia coli/Salmonella enterica serovar Typhimurium is one of the best characterized systems and serves as a model for studying the molecular mechanism by which ABC importers exert their functions. The transporter is composed of a periplasmic maltose binding protein (MalE), and a membrane-bound complex (MalFGK 2), comprising the pore-forming hydrophobic subunits, MalF and MalG, and two copies of the ABC subunit, MalK. We report on the isolation of suppressor mutations within malFG that partially restore transport of a maltose-negative mutant carrying the malK809 allele (MalKQ140K). The mutation affects the conserved LSGGQ motif that is involved in ATP binding. Three out of four suppressor mutations map in periplasmic loops P2 and P1 respectively of MalFG. Cross-linking data revealed proximity of these regions to MalE. In particular, as demonstrated in vitro and in vivo, Gly-13 of substrate-free and substrate-loaded MalE is in close contact to Pro-78 of MalG. These data suggest that MalE is permanently in close contact to MalG-P1 via its N-terminal domain. Together, our results are interpreted in favour of the notion that substrate availability is communicated from MalE to the MalK dimer via extracytoplasmic loops of MalFG, and are discussed with respect to a current transport model.

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“…Indeed, apart from the appearance of the rotational symmetry model as one of two proposed configurations of the TM α helices of Pgp [11], it has seldom been embraced by laboratories studying the topology of ABC transporters. The only two exceptions have been studies involving the maltose [25] and ribose [27] transporters. Notably, the mirror configuration has never been promoted by the authors of the cross‐linking data [13,31].…”

Section: Discussionmentioning

confidence: 99%

“…If one rejects the mirror symmetry model, then the results of one or other of these two studies must be rejected. Recent studies of other ABC transporters, such as the maltose permease [25], the histidine permease [26], the ribose permease [27], TAP [28] and CFTR [29], have all cited the EM study of Pgp in attempting to interpret their results in terms of the single‐pore, 6 + 6 TM model. Thus accepting the EM profile of Pgp means effectively either acceptance of the mirror symmetry model (Fig.…”

Section: Toroidal Pore or Cyclone Model?mentioning

confidence: 99%

Symmetry and structure in P‐glycoprotein and ABC transporters

Jones¹,

George²

2000

European Journal of Biochemistry

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The ABC superfamily of membrane transporters is one of the largest classes of proteins across all species and one of the most intensely researched. ABC proteins are involved in the trafficking of a diverse variety of biological molecules across cell membranes, with some members implicated in medical syndromes such as cystic fibrosis and multidrug resistance to anti-cancer drugs. In the absence of X-ray crystallographic data, structural information has come from spectroscopy, electron microscopy, secondary structure prediction algorithms and residue substitution, epitope labelling and cysteine cross-linking studies. These have generally supported a model for the topology of the transmembrane domains of ABC transporters in which a single aqueous pore is formed by a toroidal ring of 12 alpha helices, deployed in two arcs of six helices each. Although this so-called 6 + 6 helix model can be arranged in either mirror or rotational symmetry configurations, experimental data supports the former. In this review, we put forward arguments against both configurations of this 6 + 6 helix model, based on what is known generally about symmetry relationships in proteins. We relate these arguments to P-glycoprotein, in particular, and discuss alternative models for the structure of ABC transporters in the light of the most recent research.

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Structure-Function Study of MalF Protein by Random Mutagenesis

Cited by 22 publications

References 31 publications

Evolution of mal ABC transporter operons in the Thermococcales and Thermotogales

Evolution of mal ABC transporter operons in the Thermococcales and Thermotogales

Maltose binding protein (MalE) interacts with periplasmic loops P2 and P1 respectively of the MalFG subunits of the maltose ATP binding cassette transporter (MalFGK₂) from Escherichia coli/Salmonella during the transport cycle

Symmetry and structure in P‐glycoprotein and ABC transporters

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Structure-Function Study of MalF Protein by Random Mutagenesis

Cited by 22 publications

References 31 publications

Evolution of mal ABC transporter operons in the Thermococcales and Thermotogales

Evolution of mal ABC transporter operons in the Thermococcales and Thermotogales

Maltose binding protein (MalE) interacts with periplasmic loops P2 and P1 respectively of the MalFG subunits of the maltose ATP binding cassette transporter (MalFGK2) from Escherichia coli/Salmonella during the transport cycle

Symmetry and structure in P‐glycoprotein and ABC transporters

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Maltose binding protein (MalE) interacts with periplasmic loops P2 and P1 respectively of the MalFG subunits of the maltose ATP binding cassette transporter (MalFGK₂) from Escherichia coli/Salmonella during the transport cycle