Cell‐cycle‐dependent regulation of ornithine decarboxylase activity in the unicellular green alga Chlamydomonas reinhardtii

Abstract

Polyamines play an important role in the control of cell to the cell division phase. This up-regulation of ODC activgrowth and cell division. In the unicellular green alga ity was not due to an increased level of ODC-mRNA as revealed by northern-blot analyses, but correlated with an Chlamydomonas reinhardtii as in animal cells, biosynthesis of the 3 commonly occurring polyamines (putrescine, sper-increased half-life of this particular enzyme (from 1.1 to 3.2 h). Addition of the DNA topoisomerase II inhibitor nalidixic midine and spermine) is dependent on the activity of ornithine decarboxylase (ODC, EC 4.1.1.17) catalyzing the acid during the second half of the growth period caused a transient decrease of ODC activity and a considerable delay formation of putrescine, which is the precursor of the other two polyamines. Therefore, we have investigated the regula-of cell divisions. After cell division, a down-regulation of tion of ODC activity during the cell cycle of Clamydomonas ODC activity was observed which was faster in the dark reinhardtii using synchronized cultures. A 2.5 -3-fold in-than in the light and also correlated with changes of the ODC half-life. crease in ODC activity was observed during the transition

Regulation of polyamine metabolism in Pyropia cinnamomea (W.A. Nelson), an important mechanism for reducing UV‐B‐induced oxidative damage

“…). Contradicting reports on the presence of ADC enzyme (Voigt and Bohley ) in Chlamydomonas reinhardtii and on the absence of an ADC gene in the same green microalga (Fuell et al. ) and the lack of information on ADC and ODC gene expression in macroalgae demonstrate the necessity for uncovering the regulation of PA synthesis in macroalgae.…”

“…In general, ADC was found to be more active than ODC in plants grown under optimum conditions (Slocum and Flores 1991). Although most work indicates that ODC activity is correlated with cell division (Voigt and Bohley 2000, Guzman-Uriostegui et al 2002, Sacramento et al 2004, Gemperlova et al 2005, while ADC activity responds to different environmental stresses (Reggiani et al 1989, Foster and Walters 1991, Benavides et al 1997, Voigt and Bohley 2000, Groppa et al 2001, Mo and Pua 2002, Jantaro et al 2003, Capell et al 2004, Hao et al 2005, the opposite results may also be observed. Aziz et al (1998) exposed rape leaf disks to osmotic stress and observed decreased PA levels during two separate inhibitor treatments, demonstrating that, in fact, both enzymes are involved in the stress response.…”

“…In general, ADC was found to be more active than ODC in plants grown under optimum conditions (Slocum and Flores ). Although most work indicates that ODC activity is correlated with cell division (Voigt and Bohley , Guzman‐Uriostegui et al. , Sacramento et al.…”

“…, Foster and Walters , Benavides et al. , Voigt and Bohley , Groppa et al. , Mo and Pua , Jantaro et al.…”

“…). In Chlamydomonas reinhardtii, PAs were mainly regulated via the ODC pathway, indicated by continuously low ADC levels during light or dark treatment (Voigt and Bohley ).…”