TY - JOUR
T1 - The Pneumocystis meiotic PCRan1p kinase exhibits unique temperature-regulated activity
AU - Burgess, Joshua W.
AU - Kottom, Theodore J.
AU - Villegas, Leah R.
AU - Lamont, Jeffrey D.
AU - Baden, Elizabeth M.
AU - Ramirez-Alvarado, Marina
AU - Limper, Andrew H.
PY - 2009/12/1
Y1 - 2009/12/1
N2 - Pneumocystis organisms are opportunistic fungal pathogens that cause significant pneumonia in immune-compromised hosts. Recent evidence has suggested that Pneumocystis carinii exists as separate mating types, and expresses and regulates proteins that govern meiosis and progression of the life cycle. This study was undertaken to investigate the activity of three life cycle-regulatory proteins in Pneumocystis, including two proteins essential in mating signaling, and a putative meiotic regulator, to determine the conditions under which they are mostactive. This study used V5/HIS-tagged PCRan1p, PCSte20p, and PCCbk1, purified from Saccharomyces cerevisiae strain, INVSC, as well as an in vitro Escherichia coli protein expression system to determine the optimal expression conditions of each protein in the presence of varying pH, temperature, and metal ions. These studies demonstrate an atypical enzymatic activity in PCRan1p, whereby the kinase was most active in the environmental conditions between 10 and 25°C, compared with a dramatic reduction in activity above 30°C, temperatures typically found within mammalianhosts. Circular dichroism andfluorescence spectroscopy suggest that PCRan1p becomespartially unfoldedat 25°C, leading to its most active conformation, whereas continued unfolding as temperature increases results in strongly suppressed activity. These studies suggest that, in vivo, while under conditions within the mammalian lung (typically 37°C), PCRan1p kinase activity is largely suppressed, allowing better conditions for the activation of meiosis, whereas in ex vivo environments, PCRan1p kinase activity increases to arrest progression of the life cycle until conditions become more favorable.
AB - Pneumocystis organisms are opportunistic fungal pathogens that cause significant pneumonia in immune-compromised hosts. Recent evidence has suggested that Pneumocystis carinii exists as separate mating types, and expresses and regulates proteins that govern meiosis and progression of the life cycle. This study was undertaken to investigate the activity of three life cycle-regulatory proteins in Pneumocystis, including two proteins essential in mating signaling, and a putative meiotic regulator, to determine the conditions under which they are mostactive. This study used V5/HIS-tagged PCRan1p, PCSte20p, and PCCbk1, purified from Saccharomyces cerevisiae strain, INVSC, as well as an in vitro Escherichia coli protein expression system to determine the optimal expression conditions of each protein in the presence of varying pH, temperature, and metal ions. These studies demonstrate an atypical enzymatic activity in PCRan1p, whereby the kinase was most active in the environmental conditions between 10 and 25°C, compared with a dramatic reduction in activity above 30°C, temperatures typically found within mammalianhosts. Circular dichroism andfluorescence spectroscopy suggest that PCRan1p becomespartially unfoldedat 25°C, leading to its most active conformation, whereas continued unfolding as temperature increases results in strongly suppressed activity. These studies suggest that, in vivo, while under conditions within the mammalian lung (typically 37°C), PCRan1p kinase activity is largely suppressed, allowing better conditions for the activation of meiosis, whereas in ex vivo environments, PCRan1p kinase activity increases to arrest progression of the life cycle until conditions become more favorable.
KW - Kinase
KW - Meiosis
KW - Pneumocystis
KW - Temperature
UR - http://www.scopus.com/inward/record.url?scp=70949107672&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=70949107672&partnerID=8YFLogxK
U2 - 10.1165/rcmb.2008-0098OC
DO - 10.1165/rcmb.2008-0098OC
M3 - Article
C2 - 19286979
AN - SCOPUS:70949107672
SN - 1044-1549
VL - 41
SP - 714
EP - 721
JO - American journal of respiratory cell and molecular biology
JF - American journal of respiratory cell and molecular biology
IS - 6
ER -