Sequential metabolic events during encystment of Azobacter vinelandii.
Cells of Azotobacter vinelandii are specifically induced to encyst by beta-hydroxybutyrate (BHB). The process of differentiation, which occurs over a period of 36 h, was characterized by an ordered sequence of biochemical events. Upon initiation of encystment, nitrogen fixation and glucose-6-phosphate dehydrogenase activities decreased immediately to very low levels. This was followed by an increase in the specific activities of BHB dehydrogenase, isocitrate dehydrogenase, isocitrate lyase, and malate synthase first at 3 h and then again at 21 h. The peak activity of fructose 1,6-diphosphate aldolase occurred at 6 h, and the enzyme activity then decreased gradually. Fructose 1,6-diphosphatase had peak activities at 9 and 27 h. Deoxyribonucleic acid synthesis ceased just prior to the final cell division at 4 to 6 h, but ribonucleic acid synthesis continued until the 12th h. From labeling studies and the appearance of new enzyme activities, it appeared that protein synthesis continued throughout encystment.
D000114:Acetylene / Q000378:metabolism; D001395:Azotobacter / Q000166:cytology / Q000201:enzymology / Q000254:growth & development / Q000378:metabolism*; D001426:Bacterial Proteins / Q000096:biosynthesis; D002245:Carbon Dioxide / Q000096:biosynthesis; D002247:Carbon Isotopes; D002454:Cell Differentiation; D002474:Cell-Free System; D004269:DNA, Bacterial / Q000096:biosynthesis; D004789:Enzyme Activation; D006597:Fructose-Bisphosphatase / Q000378:metabolism; D005634:Fructose-Bisphosphate Aldolase / Q000378:metabolism; D005954:Glucosephosphate Dehydrogenase / Q000378:metabolism; D006884:Hydroxybutyrate Dehydrogenase / Q000378:metabolism; D006885:Hydroxybutyrates / Q000378:metabolism; D007521:Isocitrate Dehydrogenase / Q000378:metabolism; D007523:Isocitrates; D008293:Malates; D009024:Morphogenesis; D009586:Nitrogen Fixation; D007652:Oxo-Acid-Lyases / Q000378:metabolism; D012329:RNA, Bacterial / Q000096:biosynthesis; D013053:Spectrophotometry; D013997:Time Factors
D001426:Bacterial Proteins; D002247:Carbon Isotopes; D004269:DNA, Bacterial; D006885:Hydroxybutyrates; D007523:Isocitrates; D008293:Malates; D012329:RNA, Bacterial; D002245:Carbon Dioxide; D006884:Hydroxybutyrate Dehydrogenase; D007521:Isocitrate Dehydrogenase; D005954:Glucosephosphate Dehydrogenase; D006597:Fructose-Bisphosphatase; D005634:Fructose-Bisphosphate Aldolase; D007652:Oxo-Acid-Lyases; D000114:Acetylene