scholarly journals Structural insights into the mechanism defining substrate affinity in Arabidopsis thaliana dUTPase: the role of tryptophan 93 in ligand orientation

2015 ◽  
Vol 8 (1) ◽  
Author(s):  
Noriko Inoguchi ◽  
Kittichai Chaiseeda ◽  
Mamoru Yamanishi ◽  
Moon Ki Kim ◽  
Yunho Jang ◽  
...  
Biology ◽  
2019 ◽  
Vol 8 (4) ◽  
pp. 77
Author(s):  
Caparrós-Martín ◽  
McCarthy-Suárez ◽  
Culiáñez-Macià

The Arabidopsis thaliana broad-range sugar phosphate phosphatase AtSgpp (NP_565895.1, locus AT2G38740) and the specific DL-glycerol-3-phosphatase AtGpp (NP_568858.1, locus AT5G57440) are members of the wide family of magnesium-dependent acid phosphatases subfamily I with the C1-type cap domain haloacid dehalogenase-like hydrolase proteins (HAD). Although both AtSgpp and AtGpp have a superimporsable α/β Rossmann core active site, they differ with respect to the loop-5 of the cap domain, accounting for the differences in substrate specificity. Recent functional studies have demonstrated the essential but not sufficient role of the signature sequence within the motif-5 in substrate discrimination. To better understand the mechanism underlying the control of specificity, we explored additional sequence determinants underpinning the divergent evolutionary selection exerted on the substrate affinity of both enzymes. The most evident difference was found in the loop preceding the loop-5 of the cap domain, which is extended in three additional residues in AtSgpp. To determine if the shortening of this loop would constrain the substrate ambiguity of AtSgpp, we deleted these three aminoacids. The kinetic analyses of the resulting mutant protein AtSgpp3Δ (ΔF53, ΔN54, ΔN55) indicate that promiscuity is compromised. AtSgpp3Δ displays highest level of discrimination for D-ribose-5-phosphate compared to the rest of phosphate ester metabolites tested, which may suggest a proper orientation of D-ribose-5-phosphate in the AtSgpp3Δ active site.


Author(s):  
Rajdeep Ray ◽  
Gautham Shenoy ◽  
N V Ganesh Kumar Tummalapalli

: Tuberculosis is one of the leading cause for deaths due to infectious disease worldwide. There is an urgent need for developing new drugs due to the rising incidents of drug resistance. Triazoles have previously been reported to show antitubercular activity. Various computational tools pave the way for a rational approach in understanding the structural importance of these compounds in inhibiting Mycobacterium tuberculosis growth. The aim of this study is to develop and compare two different QSAR models based on a set of previously reported molecules and use the best one for gaining structural insights in to the Triazole molecules. In the current study, two separate models were generated with CoMFA and CoMSIA descriptors respectively based on a dataset of triazole molecules showing antitubercular activity. Several one dimensional (1D) descriptors were added to each of the models and the validation results and the contour data generated from them were compared. The best model was studied to give a detailed understanding of the triazole molecules and their role in the antitubercular activity.The r2, q2, predicted r2 and SEP (Standard error of prediction) for the CoMFA model were 0.866, 0.573, 0.119 and 0.736 respectively and for the CoMSIA model the r2, q2, predicted r2 and SEP were calculated to be 0.998, 0.634, 0.013 and 0.869 respectively. Although both the QSAR models produced acceptable internal and external validation scores but the CoMSIA results were significantly better. The CoMSIA contours also provided a better match than CoMFA with most of the features of the active compound 30b. Hence, the CoMSIA model was chosen and its contours were explored for gaining structural insights on the triazole molecules. The CoMSIA contours helped us to understand the role of several atoms and groups of the triazole molecules in their biological activity. The possibilities for substitution in the triazole compounds that would enhance the activity were also analysed. Thus, this study paves the way for designing new antitubercular drugs in future.


2020 ◽  
Vol 44 (1) ◽  
pp. 114-129
Author(s):  
Jing‐Wen Yao ◽  
Zheng Ma ◽  
Yan‐Qin Ma ◽  
Ying Zhu ◽  
Meng‐Qi Lei ◽  
...  

Dose-Response ◽  
2020 ◽  
Vol 18 (4) ◽  
pp. 155932582097924
Author(s):  
Darya Babina ◽  
Marina Podobed ◽  
Ekaterina Bondarenko ◽  
Elizaveta Kazakova ◽  
Sofia Bitarishvili ◽  
...  

Plant growth response to γ-irradiation includes stimulating or inhibitory effects depending on plant species, dose applied, stage of ontogeny and other factors. Previous studies showed that responses to irradiation could depend on ABA accumulation and signaling. To elucidate the role of ABA in growth and photosynthetic responses to irradiation, lines Col-8, abi3-8 and aba3 -1 of Arabidopsis thaliana were used. Seeds were γ-irradiated using 60Co in the dose range 50-150 Gy. It was revealed that the dose of 150 Gy affected germination parameters of aba3 -1 and Col-8 lines, while abi3-8 line was the most resistant to the studied doses and even showed faster germination at early hours after γ-irradiation at 50 Gy. These results suggest that susceptibility to ABA is probably more important for growth response to γ-irradiation than ABA synthesis. The photosynthetic functioning of 16-day-old plants mainly was not disturbed by γ-irradiation of seeds, and no indication of photosystem II photoinhibition was noticed, revealing the robustness of the photosynthetic system of A. thaliana. Glutathione peroxidase activity and ABA concentrations in plant tissues were not affected in the studied dose range. These results contribute to the understanding of germination and photosynthesis fine-tuning and of mechanisms of plant tolerance to ionizing radiation.


2015 ◽  
Vol 90 (3) ◽  
pp. 163-174
Author(s):  
Hiroaki Kato ◽  
Yoshibumi Komeda ◽  
Tamao Saito ◽  
Hidetaka Ito ◽  
Atsushi Kato

Sign in / Sign up

Export Citation Format

Share Document