title: Structurally disordered C-terminal residues of GTP cyclohydrolase II are essential for its enzymatic activity
creator: Yadav,  Savita
creator: Shinde,  Ranajit Nivrutti
creator: Singh, Suruchi
creator: Karthikeyan, Subramanian
creator: Singh, Balvinder
subject: QR Microbiology
description: GTP cyclohydrolase II (GCHII) is one of the rate limiting enzymes in riboflavin biosynthesis pathway and is shown to be a potential drug target for most of the pathogens. Previous biochemical and structural studies have identified the active site residues and elucidated the steps involved in the catalytic mechanism of GCHII. However, the last similar to 20-25 C-terminal residues of GCHII remains unstructured in all the crystal structures determined to date and their role in the catalytic activity, if any, remains elusive. Therefore, to understand the role of these unstructured C-terminal residues, a series of C-terminal deletion mutants of GCHII from Helicobacter pylori (hGCHII) were generated and their catalytic activity was compared with its wild-type. Surprisingly, none of the C-terminal deletion mutants shows any enzymatic activity indicating that these are essential for GCHII function. To get additional insights for such loss of activity, homology models of full-length and deletion mutants of hGCHII in complex with GTP, Mg2+, and Zn2+ were generated and subjected to molecular dynamics simulation studies. The simulation studies show that a conserved histidine at 190(th) position from the unstructured C-terminal region of hGCHII interacts with alpha-phosphate of GTP. We propose that His-190 may play a role in the hydrolysis of pyrophosphate from GTP and in releasing the product, DARP. In summary, we demonstrate that the unstructured C-terminal residues of GCHII are important for its enzymatic activity and must be considered during rational drug designing. Communicated by Ramaswamy H. Sarma
publisher: Taylor & Francis
date: 2021-05
type: Article
type: PeerReviewed
relation: https://pubmed.ncbi.nlm.nih.gov/34032179/
identifier:   Yadav, Savita and Shinde, Ranajit Nivrutti and Singh, Suruchi and Karthikeyan, Subramanian and Singh, Balvinder  (2021) Structurally disordered C-terminal residues of GTP cyclohydrolase II are essential for its enzymatic activity.  Journal of biomolecular structure & dynamics.   ISSN 1538-0254     
relation: http://crdd.osdd.net/open/2695/