TY - JOUR
T1 - A functional calcium-transporting ATPase encoded by chlorella viruses
AU - Bonza, Maria Cristina
AU - Martin, Holger
AU - Kang, Ming
AU - Lewis, Gentry
AU - Greiner, Timo
AU - Giacometti, Sonia
AU - Van Etten, James L.
AU - De Michelis, Maria Ida
AU - Thiel, Gerhard
AU - Moroni, Anna
PY - 2010/10
Y1 - 2010/10
N2 - Calcium-transporting ATPases (Ca2+ pumps) are major players in maintaining calcium homeostasis in the cell and have been detected in all cellular organisms. Here, we report the identification of two putative Ca 2+ pumps, M535L and C785L, encoded by chlorella viruses MT325 and AR158, respectively, and the functional characterization of M535L. Phylogenetic and sequence analyses place the viral proteins in group IIB of P-type ATPases even though they lack a typical feature of this class, a calmodulin-binding domain. A Ca2+ pump gene is present in 45 of 47 viruses tested and is transcribed during virus infection. Complementation analysis of the triple yeast mutant K616 confirmed that M535L transports calcium ions and, unusually for group IIB pumps, also manganese ions. In vitro assays show basal ATPase activity. This activity is inhibited by vanadate, but, unlike that of other Ca2+ pumps, is not significantly stimulated by either calcium or manganese. The enzyme forms a 32P-phosphorylated intermediate, which is inhibited by vanadate and not stimulated by the transported substrate Ca 2+, thus confirming the peculiar properties of this viral pump. To our knowledge this is the first report of a functional P-type Ca 2+-transporting ATPase encoded by a virus.
AB - Calcium-transporting ATPases (Ca2+ pumps) are major players in maintaining calcium homeostasis in the cell and have been detected in all cellular organisms. Here, we report the identification of two putative Ca 2+ pumps, M535L and C785L, encoded by chlorella viruses MT325 and AR158, respectively, and the functional characterization of M535L. Phylogenetic and sequence analyses place the viral proteins in group IIB of P-type ATPases even though they lack a typical feature of this class, a calmodulin-binding domain. A Ca2+ pump gene is present in 45 of 47 viruses tested and is transcribed during virus infection. Complementation analysis of the triple yeast mutant K616 confirmed that M535L transports calcium ions and, unusually for group IIB pumps, also manganese ions. In vitro assays show basal ATPase activity. This activity is inhibited by vanadate, but, unlike that of other Ca2+ pumps, is not significantly stimulated by either calcium or manganese. The enzyme forms a 32P-phosphorylated intermediate, which is inhibited by vanadate and not stimulated by the transported substrate Ca 2+, thus confirming the peculiar properties of this viral pump. To our knowledge this is the first report of a functional P-type Ca 2+-transporting ATPase encoded by a virus.
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U2 - 10.1099/vir.0.021873-0
DO - 10.1099/vir.0.021873-0
M3 - Article
C2 - 20573858
AN - SCOPUS:77956849497
SN - 0022-1317
VL - 91
SP - 2620
EP - 2629
JO - Journal of General Virology
JF - Journal of General Virology
IS - 10
ER -