scholarly journals Periplasmic binding protein dependent transport system for maltose and maltodextrins: some recent studies

1989 ◽  
Vol 63 (1-2) ◽  
pp. 53-60
Author(s):  
W. Saurin ◽  
E. Francoz ◽  
P. Martineau ◽  
A. Charbit ◽  
E. Dassa ◽  
...  
Keyword(s):  
Transport System ◽  
Binding Protein ◽  
Periplasmic Binding Protein ◽  
Dependent Transport

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 NasFED Proteins Mediate Assimilatory Nitrate and Nitrite Transport in Klebsiella oxytoca(pneumoniae) M5al

1998 ◽  
Vol 180 (5) ◽  
pp. 1311-1322 ◽  
Author(s):  
Qitu Wu ◽  
Valley Stewart
Keyword(s):  
Binding Protein ◽  
Klebsiella Oxytoca ◽  
Nitrogen Sources ◽  
Nitrate Transport ◽  
Periplasmic Binding Protein ◽  
Sequence Comparisons ◽  
Abc Protein ◽  
Nitrite Transport ◽  
Dependent Transport ◽  
Nitrate And Nitrite

ABSTRACT Klebsiella oxytoca can use nitrate and nitrite as sole nitrogen sources. The enzymes required for nitrate and nitrite assimilation are encoded by the nasFEDCBA operon. We report here the complete nasFED sequence. Sequence comparisons indicate that the nasFED genes encode components of a conventional periplasmic binding protein-dependent transport system consisting of a periplasmic binding protein (NasF), a homodimeric intrinsic membrane protein (NasE), and a homodimeric ATP-binding cassette (ABC) protein (NasD). The NasF protein and the related NrtA and CmpA proteins of cyanobacteria contain leader (signal) sequences with the double-arginine motif that is hypothesized to direct prefolded proteins to an alternate protein export pathway. The NasE protein and the related NrtB and CmpB proteins of cyanobacteria contain unusual variants of the EAA loop sequence that defines membrane-intrinsic proteins of ABC transporters. To characterize nitrate and nitrite transport, we constructed in-frame nonpolar deletions of the chromosomal nasFED genes. Growth tests coupled with nitrate and nitrite uptake assays revealed that the nasFED genes are essential for nitrate transport and participate in nitrite transport as well. Interestingly, the ΔnasF strain exhibited leaky phenotypes, particularly at elevated nitrate concentrations, suggesting that the NasED proteins are not fully dependent on the NasF protein.

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