Mathematical modeling of the low and high affinity arabinose transport systems in Escherichia coli

2012 ◽  
Vol 8 (4) ◽  
pp. 1319 ◽  
Author(s):  
Necmettin Yildirim
Keyword(s):  
Mathematical Modeling ◽  
Escherichia Coli ◽  
Transport Systems ◽  
High Affinity

scholarly journals Structure of an ABC transporter solute-binding protein specific for the amino sugars glucosamine and galactosamine

2016 ◽  
Vol 72 (6) ◽  
pp. 467-472 ◽  
Author(s):  
Umesh Yadava ◽  
Matthew W. Vetting ◽  
Nawar Al Obaidi ◽  
Michael S. Carter ◽  
John A. Gerlt ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Binding Protein ◽  
Transport Systems ◽  
Amino Sugars ◽  
Ligand Binding Site ◽  
Agrobacterium Vitis ◽  
High Affinity ◽  
Differential Scanning Fluorimetry ◽  
Membrane Bound ◽  
Ribose Binding Protein

The uptake of exogenous solutes by prokaryotes is mediated by transport systems embedded in the plasma membrane. In many cases, a solute-binding protein (SBP) is utilized to bind ligands with high affinity and deliver them to the membrane-bound components responsible for translocation into the cytoplasm. In the present study, Avi_5305, anAgrobacterium vitisSBP belonging to Pfam13407, was screened by differential scanning fluorimetry (DSF) and found to be stabilized by D-glucosamine and D-galactosamine. Avi_5305 is the first protein from Pfam13407 shown to be specific for amino sugars, and co-crystallization resulted in structures of Avi_5305 bound to D-glucosamine and D-galactosamine. Typical of Pfam13407, Avi_5305 consists of two α/β domains linked through a hinge region, with the ligand-binding site located in a cleft between the two domains. Comparisons withEscherichia coliribose-binding protein suggest that a cation–π interaction with Tyr168 provides the specificity for D-glucosamine/D-galactosamine over D-glucose/D-galactose.

scholarly journals The STK2 gene, which encodes a putative Ser/Thr protein kinase, is required for high-affinity spermidine transport in Saccharomyces cerevisiae.

1997 ◽  
Vol 17 (6) ◽  
pp. 2994-3004 ◽  
Author(s):  
M Kaouass ◽  
M Audette ◽  
D Ramotar ◽  
S Verma ◽  
D De Montigny ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Protein Kinase ◽  
Fusion Gene ◽  
Transport Systems ◽  
Coding Region ◽  
Kinase Gene ◽  
Lower Affinity ◽  
High Affinity ◽  
Polyamine Transport ◽  
Exogenous Spermidine

Eukaryotic polyamine transport systems have not yet been characterized at the molecular level. We have used transposon mutagenesis to identify genes controlling polyamine transport in Saccharomyces cerevisiae. A haploid yeast strain was transformed with a genomic minitransposon- and lacZ-tagged library, and positive clones were selected for growth resistance to methylglyoxal bis(guanylhydrazone) (MGBG), a toxic polyamine analog. A 747-bp DNA fragment adjacent to the lacZ fusion gene rescued from one MGBG-resistant clone mapped to chromosome X within the coding region of a putative Ser/Thr protein kinase gene of previously unknown function (YJR059w, or STK2). A 304-amino-acid stretch comprising 11 of the 12 catalytic subdomains of Stk2p is approximately 83% homologous to the putative Pot1p/Kkt8p (Stk1p) protein kinase, a recently described activator of low-affinity spermine uptake in yeast. Saturable spermidine transport in stk2::lacZ mutants had an approximately fivefold-lower affinity and twofold-lower Vmax than in the parental strain. Transformation of stk2::lacZ cells with the STK2 gene cloned into a single-copy expression vector restored spermidine transport to wild-type levels. Single mutants lacking the catalytic kinase subdomains of STK1 exhibited normal parameters for the initial rate of spermidine transport but showed a time-dependent decrease in total polyamine accumulation and a low-level resistance to toxic polyamine analogs. Spermidine transport was repressed by prior incubation with exogenous spermidine. Exogenous polyamine deprivation also derepressed residual spermidine transport in stk2::lacZ mutants, but simultaneous disruption of STK1 and STK2 virtually abolished high-affinity spermidine transport under both repressed and derepressed conditions. On the other hand, putrescine uptake was also deficient in stk2::lacZ mutants but was not repressed by exogenous spermidine. Interestingly, stk2::lacZ mutants showed increased growth resistance to Li+ and Na+, suggesting a regulatory relationship between polyamine and monovalent inorganic cation transport. These results indicate that the putative STK2 Ser/Thr kinase gene is an essential determinant of high-affinity polyamine transport in yeast whereas its close homolog STK1 mostly affects a lower-affinity, low-capacity polyamine transport activity.

Properties of the high-affinity single-stranded DNA binding state of the Escherichia coli recA protein

Biochemistry ◽  
1988 ◽  
Vol 27 (4) ◽  
pp. 1205-1212 ◽  
Author(s):  
Joseph P. Menetski ◽  
Abraham Varghese ◽  
Stephen C. Kowalczykowski
Keyword(s):  
Escherichia Coli ◽  
Dna Binding ◽  
Reca Protein ◽  
Single Stranded Dna ◽  
High Affinity
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