Evolutionary analysis of a novel zinc ribbon in the N-terminal region of threonine synthase

Kaur, G. and Subramanian, Srikrishna (2017) Evolutionary analysis of a novel zinc ribbon in the N-terminal region of threonine synthase. Cell Cycle, 16 (20). pp. 1918-1926. ISSN 1538-4101

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Official URL: http://dx.doi.org/10.1080/15384101.2017.1363937


Threonine synthase (TS) catalyzes the terminal reaction in the biosynthetic pathway of threonine and requires pyridoxal phosphate as a cofactor. TSs share a common catalytic domain with other fold type II PALP dependent enzymes. TSs are broadly grouped into two classes based on their sequence, quaternary structure, and enzyme regulation. We report the presence of a novel zinc ribbon domain in the N-terminal region preceding the catalytic core in TS. The zinc ribbon domain is present in TSs belonging to both classes. Our sequence analysis reveals that archaeal TSs possess all zinc chelating residues to bind a metal ion that are lacking in the structurally characterized homologs. Phylogenetic analysis suggests that TSs with an N-terminal zinc ribbon likely represents the ancestral state of the enzyme while TSs without a zinc ribbon must have diverged later in specific lineages. The zinc ribbon and its N- and C-terminal extensions are important for enzyme stability, activity and regulation. It is likely that the zinc ribbon domain is involved in higher order oligomerization or mediating interactions with other biomolecules leading to formation of larger metabolic complexes.

Item Type: Article
Additional Information: Copyright of this article belongs to Landes Bioscience.
Uncontrolled Keywords: PLP-dependent enzymes; SAM-regulated enzymes; Zinc fingers; allosteric regulation; protein evolution
Subjects: Q Science > QR Microbiology
Depositing User: Dr. K.P.S.Sengar
Date Deposited: 28 Mar 2018 03:33
Last Modified: 28 Mar 2018 04:35
URI: http://crdd.osdd.net/open/id/eprint/2036

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