Study on the mechanism of the BtuF periplasmic-binding protein for vitamin B12

2008 ◽  
Vol 135 (1-3) ◽  
pp. 19-24 ◽  
Author(s):  
Ming Liu ◽  
TingGuang Sun ◽  
JianPing Hu ◽  
WeiZu Chen ◽  
CunXin Wang
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Elif Börekci ◽  
Mahmut Kılıç ◽  
Zeynep Ozan ◽  
Hasan Börekci ◽  
Tekin Yıldırım ◽  
...  

Abstract Objectives There is no reliable and valid biomarker to identify Irritable bowel syndrome (IBS) and its subtypes. The aim of this study is to explore potential serum biomarkers that may be associated with IBS subtypes, particularly in the vitamin D pathway. Methods The study population comprised 75 IBS patients and 79 controls. Patients divided into IBS subtypes. Routine biochemical parameters, 25-OH-vitamin D, vitamin D binding protein (VDBP) and vitamin D receptor (VDR) serum levels were compared between IBS subtypes and controls. Factors related to IBS subtypes were examined by multivariate logistic regression analysis. Results Vitamin D levels were lower; VDBP and VDR were higher in all IBS patients than in controls (p<0.001; 0.047 and 0.029, respectively). According to logistic regression analysis, VDBP was a disease-related parameter as much as vitamin D in all IBS subtypes. C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) were higher especially in diarrhea-dominant IBS (IBS-D) (p=0.041; 0.046) and vitamin B12 were significantly lower in constipation-dominant IBS (IBS-C) (p=0.001). Conclusions Increased VDBP levels were associated with all IBS subtypes. Patients, especially in IBS-D, had higher serum levels of VDBP, CRP and ESR. Vitamin B12 deficiency, which we consider as a result of the disease, was more common in IBS-C.


1989 ◽  
Vol 63 (1-2) ◽  
pp. 53-60
Author(s):  
W. Saurin ◽  
E. Francoz ◽  
P. Martineau ◽  
A. Charbit ◽  
E. Dassa ◽  
...  

2001 ◽  
Vol 79 (8) ◽  
pp. 692-704 ◽  
Author(s):  
Focco van den Akker

The X-ray crystal structure of the dimerized atrial natriuretic factor (ANF) receptor hormone-binding domain has provided a first structural view of this anti-hypertensive receptor. The structure reveals a surprising evolutionary link to the periplasmic-binding protein fold family. Furthermore, the presence of a chloride ion in the membrane distal domain and the presence of a second putative effector pocket suggests that the extracellular domain of this receptor is allosterically regulated. The scope of this article is to extensively review the data published on this receptor and to correlate it with the hormone-binding domain structure. In addition, a more detailed description is provided of the important features of this structure including the different binding sites for the ANF hormone, chloride ion, putative effector pocket, glycosylation sites, and dimer interface.Key words: crystal structure, periplasmic-binding protein fold, guanylyl cyclase, hormone receptor.


2009 ◽  
Vol 75 (3) ◽  
pp. 598-609 ◽  
Author(s):  
Rong Shi ◽  
Ariane Proteau ◽  
John Wagner ◽  
Qizhi Cui ◽  
Enrico O. Purisima ◽  
...  

2000 ◽  
Vol 182 (13) ◽  
pp. 3717-3725 ◽  
Author(s):  
Eric Boncompagni ◽  
Laurence Dupont ◽  
Tam Mignot ◽  
Magne Østeräs ◽  
Annie Lambert ◽  
...  

ABSTRACT The symbiotic soil bacterium Sinorhizobium melilotiuses the compatible solutes glycine betaine and proline betaine for both protection against osmotic stress and, at low osmolarities, as an energy source. A PCR strategy based on conserved domains in components of the glycine betaine uptake systems from Escherichia coli(ProU) and Bacillus subtilis (OpuA and OpuC) allowed us to identify a highly homologous ATP-binding cassette (ABC) binding protein-dependent transporter in S. meliloti. This system was encoded by three genes (hutXWV) of an operon which also contained a fourth gene (hutH2) encoding a putative histidase, which is an enzyme involved in the first step of histidine catabolism. Site-directed mutagenesis of the gene encoding the periplasmic binding protein (hutX) and of the gene encoding the cytoplasmic ATPase (hutV) was done to study the substrate specificity of this transporter and its contribution in betaine uptake. These mutants showed a 50% reduction in high-affinity uptake of histidine, proline, and proline betaine and about a 30% reduction in low-affinity glycine betaine transport. When histidine was used as a nitrogen source, a 30% inhibition of growth was observed inhut mutants (hutX and hutH2). Expression analysis of the hut operon determined using ahutX-lacZ fusion revealed induction by histidine, but not by salt stress, suggesting this uptake system has a catabolic role rather than being involved in osmoprotection. To our knowledge, Hut is the first characterized histidine ABC transporter also involved in proline and betaine uptake.


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