Thermoplasma volcanium is one of a small number of archaea able to live in anaerobic as well as aerobic environments. By sequencing spots in 2D gels, proteins expressed in this archaeon under the two conditions, aerobic or anaerobic, were identified. In the aerobic condition, types of proteins reducing active oxygens and the archaeal chaperonin refolding denatured proteins were identified as expressed in larger quantities. Two enzymes, L-asparaginase and an iron-molybdenium cluster-binding protein, were expressed, mediating pathways from nitrate to the TCA cycle, thereby activating aerobic proton transport for ATP synthesis. Under the anaerobic condition, a transcription factor in the FFRP family, TvFL5, and another protein making disulfide bonds in other proteins were expressed. So were types of enzymes that reduce anaerobic ferredoxin in order to activate anaerobic proton transport for ATP synthesis. Another type of ferredoxin containing zinc, and a flavoprotein, reducing possibly this ferredoxin, were expressed constitutively, probably for activating proton transport also in the aerobic condition. Five hours after changing the condition from aerobic to anaerobic, many of the aerobic proteins were still present, and in addition, the anaerobic proteins were expressed.
(Communicated by Masanori OTSUKA, M.J.A.)
2005 The Japan Academy