The gluEMP operon from Zymomonas mobilis encodes a high-affinity glutamate carrier with similiarity to binding-protein-dependent transport systems

1996 ◽  
Vol 165 (5) ◽  
pp. 325-332 ◽  
Author(s):  
N. Peekhaus ◽  
Reinhard Krämer
Keyword(s):  
Zymomonas Mobilis ◽  
Binding Protein ◽  
Transport Systems ◽  
High Affinity ◽  
Dependent Transport

scholarly journals Redundancy in Periplasmic Binding Protein-Dependent Transport Systems for Trehalose, Sucrose, and Maltose in Sinorhizobium meliloti

2002 ◽  
Vol 184 (11) ◽  
pp. 2978-2986 ◽  
Author(s):  
John Beck Jensen ◽  
N. Kent Peters ◽  
T. V. Bhuvaneswari
Keyword(s):  
Nitrogen Fixation ◽  
Sinorhizobium Meliloti ◽  
Binding Protein ◽  
Regulatory Protein ◽  
Gene Replacement ◽  
Transport Systems ◽  
Atp Binding ◽  
Dependent Transport ◽  
Atp Binding Protein ◽  
Growth Experiments

ABSTRACT We have identified a cluster of six genes involved in trehalose transport and utilization (thu) in Sinorhizobium meliloti. Four of these genes, thuE, -F, -G, and -K, were found to encode components of a binding protein-dependent trehalose/maltose/sucrose ABC transporter. Their deduced gene products comprise a trehalose/maltose-binding protein (ThuE), two integral membrane proteins (ThuF and ThuG), and an ATP-binding protein (ThuK). In addition, a putative regulatory protein (ThuR) was found divergently transcribed from the thuEFGK operon. When the thuE locus was inactivated by gene replacement, the resulting S. meliloti strain was impaired in its ability to grow on trehalose, and a significant retardation in growth was seen on maltose as well. The wild type and the thuE mutant were indistinguishable for growth on glucose and sucrose. This suggested a possible overlap in function of the thuEFGK operon with the aglEFGAK operon, which was identified as a binding protein-dependent ATP-binding transport system for sucrose, maltose, and trehalose. The Km s for trehalose transport were 8 ± 1 nM and 55 ± 5 nM in the uninduced and induced cultures, respectively. Transport and growth experiments using mutants impaired in either or both of these transport systems show that these systems form the major transport systems for trehalose, maltose, and sucrose. By using a thuE′-lacZ fusion, we show that thuE is induced only by trehalose and not by cellobiose, glucose, maltopentaose, maltose, mannitol, or sucrose, suggesting that the thuEFGK system is primarily targeted toward trehalose. The aglEFGAK operon, on the other hand, is induced primarily by sucrose and to a lesser extent by trehalose. Tests for root colonization, nodulation, and nitrogen fixation suggest that uptake of disaccharides can be critical for colonization of alfalfa roots but is not important for nodulation and nitrogen fixation per se.

Periplasmic binding protein-dependent transport systems: the membrane-associated components

1990 ◽  
Vol 326 (1236) ◽  
pp. 353-365 ◽  
Keyword(s):  
Transport System ◽  
Atp Hydrolysis ◽  
Binding Protein ◽  
Primary Source ◽  
Energy Coupling ◽  
Transport Systems ◽  
Common Mechanism ◽  
Atp Binding ◽  
Periplasmic Binding Protein ◽  
Dependent Transport

Periplasmic binding protein-dependent transport systems are multicomponent, consisting of several inner membrane-associated proteins and a periplasmic component. The membrane-associated components of different systems are related in organization and function suggesting that, despite different substrate specificities, each transport system functions by a common mechanism. Current understanding of these components is reviewed. The nature of energy coupling to periplasmic transport systems has long been debated. Recent data now demonstrate that ATP hydrolysis is the primary source of energy for transport. The ATP-binding transport components are the best characterized of a family of closely related ATP-binding proteins believed to couple ATP hydrolysis to a variety of different biological processes. Intriguingly, systems closely related to periplasmic binding protein-dependent transport systems have recently been identified in several Gram-positive organisms (which lack a periplasm) and in eukaryotic cells. This class of transport system appears to be widespread in nature, serving a variety of important and diverse functions.

scholarly journals The d-Xylose-Binding Protein, XylF, from Thermoanaerobacter ethanolicus 39E: Cloning, Molecular Analysis, and Expression of the Structural Gene

1998 ◽  
Vol 180 (14) ◽  
pp. 3570-3577 ◽  
Author(s):  
Milutin Erbeznik ◽  
Herbert J. Strobel ◽  
Karl A. Dawson ◽  
Chris R. Jones
Keyword(s):  
Amino Acid ◽  
Binding Proteins ◽  
Binding Protein ◽  
Xylose Isomerase ◽  
Thermophilic Bacterium ◽  
Transport Systems ◽  
Uptake System ◽  
Calculated Molecular Mass ◽  
Thermoanaerobacter Ethanolicus ◽  
High Affinity

ABSTRACT Immediately downstream from the Thermoanaerobacter ethanolicus xylAB operon, comprising genes that encoded-xylose isomerase and d-xylulose kinase, lies a 1,101-bp open reading frame that exhibits 61% amino acid sequence identity to the Escherichia coli d-xylose binding periplasmic receptor, XylF, a component of the high-affinity binding-protein-dependent d-xylose transport. The 25-residue N-terminal fragment of the deduced T. ethanolicus XylF has typical features of bacterial leader peptides. The C-terminal portion of this leader sequence matches the cleavage consensus for lipoproteins and is followed by a 22-residue putative linker sequence rich in serine, threonine, and asparagine. The putative mature 341-amino-acid-residue XylF (calculated molecular mass of 37,069 Da) appears to be a lipoprotein attached to the cell membrane via a lipid anchor covalently linked to the N-terminal cysteine, as demonstrated by metabolic labelling of the recombinant XylF with [14C]palmitate. The induced E. coli avidly bound d-[14C]xylose, yielding additional evidence that T. ethanolicus XylF is thed-xylose-binding protein. On the basis of sequence comparison of XylFs to other monosaccharide-binding proteins, we propose that the sequence signature of binding proteins specific for hexoses and pentoses be refined as (KDQ)(LIVFAG)3IX3(DN)(SGP)X3(GS)X(LIVA)2X2A. Transcription of the monocistronic 1.3-kb xylF mRNA is inducible by xylose and unaffected by glucose. Primer extension analysis indicated that xylF transcription initiates from two +1 sites, both situated within the xylAB operon. Unlike in similar transport systems in other bacteria, the genes specifying the membrane components (e.g., ATP-binding protein and permease) of the high-affinity d-xylose uptake system are not located in the vicinity of xylF in T. ethanolicus. This is the first report of a gene encoding a xylose-binding protein in a gram-positive or thermophilic bacterium.

Binding protein-dependent transport systems

1990 ◽  
Vol 22 (4) ◽  
pp. 571-592 ◽  
Author(s):  
C. F. Higgins ◽  
S. C. Hyde ◽  
M. M. Mimmack ◽  
U. Gileadi ◽  
D. R. Gill ◽  
...  
Keyword(s):  
Binding Protein ◽  
Transport Systems ◽  
Dependent Transport
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