RRC ID 55999
Author Honda A, Chigwechokha PK, Kamada-Futagami Y, Komatsu M, Shiozaki K.
Title Unique nuclear localization of Nile tilapia (Oreochromis niloticus) Neu4 sialidase is regulated by nuclear transport receptor importin α/β.
Journal Biochimie
Abstract Sialidase catalyzes the removal of sialic acids from glycoconjugates. Different from Neu1 and Neu3 sialidases, Neu4 enzymatic properties such as substrate specificity and subcellular localization are not well-conserved among vertebrates. In fish only zebrafish and medaka neu4 genes have been cloned and their polypeptides have been characterized so far. Thus, characterization of Neu4 from other fish species is necessary to evaluate Neu4 physiological functions. Here, Nile tilapia was chosen for the characterization of Neu4 polypeptide considering that it is one of the major cultured fish all over the world and that its genomic sequences are now available. Coding DNA sequence of tilapia Neu4 was identified as 1,497 bp and its recombinant protein showed broad substrate specificity and optimal sialidase enzyme activity pH at 4.0. Neu4 activity was sustained even in neutral and alkali pH. Interestingly, immunofluorescence analysis revealed that major subcellular localization of tilapia Neu4 was nuclear, quite distinct from zebrafish (ER) and medaka Neu4 (lysosome). Bioinformatic analysis showed the existence of putative nuclear localization signal (NLS) in tilapia Neu4. In general, it is known that importin families bind to several proteins via NLS and transfer them into nucleus. Therefore, to determine the involvement of putative NLS in Neu4 nuclear localization, Neu4 mutant deleting NLS was constructed and expressed in cultured cells. As a result, NLS deletion significantly diminished the nuclear localization. Furthermore, treatment of importazole, interrupter of binding importin β and RanGTP, significantly suppressed Neu4 nuclear localization. In summary, tilapia Neu4 is a unique sialidase localized at nucleus and its transport system into nucleus is regulated by importin.
Volume 149
Pages 92-104
Published 2018-6
DOI 10.1016/j.biochi.2018.04.003
PII S0300-9084(18)30089-0
PMID 29635043
MeSH Active Transport, Cell Nucleus / genetics Animals Cichlids / genetics* Neuraminidase / chemistry* Neuraminidase / genetics Neuraminidase / isolation & purification Nuclear Localization Signals / chemistry* Nuclear Localization Signals / genetics Oryzias / genetics Peptides / chemistry Protein Binding / drug effects Quinazolines / pharmacology Sialic Acids / chemistry Sialic Acids / metabolism Substrate Specificity Zebrafish / genetics beta Karyopherins / chemistry* beta Karyopherins / genetics
IF 3.362
Times Cited 4
Human and Animal Cells Hepa-T1(RCB1156)