The acidic amino acid-rich C-terminal domain of VanabinX enhances reductase activity, attaining 1.3- to 1.7-fold vanadium reduction

Adi, Tri Kustono, Fujie, Manabu, Satoh, Nori and Ueki, Tatsuya (2022) The acidic amino acid-rich C-terminal domain of VanabinX enhances reductase activity, attaining 1.3- to 1.7-fold vanadium reduction. Biochemistry and Biophysics Reports, 32 (101349). ISSN 24055808

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Abstract

Ascidians accumulate extremely high levels of vanadium (V) in their blood cells. Several V-related proteins,
including V-binding proteins (vanabins), have been isolated from V-accumulating ascidians. In this study, to
obtain a deeper understanding of vanabins, we performed de novo transcriptome analysis of blood cells from a Vrich
ascidian, Ascidia sydneiensis samea, and constructed a database containing 8532 predicted proteins. We
found a novel vanabin with a unique acidic amino acid–rich C-terminal domain, designated VanabinX, in the
database and studied it in detail. Reverse-transcription polymerase chain reaction analysis revealed that VanabinX
was detected in all adult tissues examined, and was most prominent in blood cells and muscle tissue. We
prepared recombinant proteins and performed immobilized metal ion affinity chromatography and a NADPHcoupled
V(V)-reductase assay. VanabinX bound to metal ions, with increasing affinity for Cu(II) > Zn(II) > Co
(II), but not to V(IV). VanabinX reduced V(V) to V(IV) at a rate of 0.170 μM per micoromolar protein within 30
min. The C-terminal acidic domain enhanced the reduction of V(V) by Vanabin2 to 1.3-fold and of VanabinX
itself to 1.7-fold in trans mode. In summary, we constructed a protein database containing 8532 predicted
proteins expressed in blood cells; among them, we discovered a novel vanabin, VanabinX, which enhances V
reduction by vanabins.

Item Type:	Journal Article
Keywords:	Next-generation sequencing Metal accumulation Metal transporters Metal binding Enzyme kinetics
Subjects:	03 CHEMICAL SCIENCES > 0304 Medicinal and Biomolecular Chemistry > 030406 Proteins and Peptides 03 CHEMICAL SCIENCES > 0305 Organic Chemistry > 030502 Natural Products Chemistry 03 CHEMICAL SCIENCES > 0305 Organic Chemistry
Divisions:	Faculty of Mathematics and Sciences > Department of Chemistry
Depositing User:	Tri Kustono Adi
Date Deposited:	30 Jan 2024 15:42

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