S11.37 Ultrafast ligand binding dynamics in the active site of native bacterial nitric oxide reductase

Prochlorococcus and Synechococcus have Evolved Different Adaptive Mechanisms to Cope with Light and UV Stress

“…PCC 7942; Golden et al, 1989), with one co-transcribed with psbC that encodes the internal PSII antenna protein CP43 (Garczarek et al, 2001) and the other isolated in the genome. It is likely that as for psbA , the two copies are differently regulated in response to light and/or UV stress as previously reported in freshwater model cyanobacteria (Bustos and Golden, 1992; Kos et al, 2008), although this was not checked in the present study. Alternatively, this may simply contribute to a higher expression level of this key photosynthetic gene, possibly enabling a higher turnover of the corresponding protein.…”

“…Indeed, while Prochlorococcus strains have one to three identical psbA gene copies (one in PCC 9511), coding for a single D1:1-like isoform (Hess et al, 1995; Partensky and Garczarek, 2003), Synechococcus strains possess three to six psbA genes, with only one copy coding for a D1:1 isoform and two to five copies (three in WH7803), coding for D1:2 isoforms (Garczarek et al, 2008). The respective role of these isoforms has been widely studied in the literature, both in freshwater cyanobacteria (Bustos et al, 1990; Clarke et al, 1993; Campbell et al, 1995, 1998a; Sass et al, 1997; Kos et al, 2008) and in marine picocyanobacteria (Garcia-Fernandez et al, 1998; Garczarek et al, 2008). Although some variations among cyanobacteria have been observed, it is generally accepted that the D1:1 isoform would confer a higher PSII activity (Campbell et al, 1996), while D1:2 would provide a lower quantum yield but a higher PSII resistance to photoinhibition (Krupa et al, 1991;Campbell et al, 1995, 1998a; Tichy et al, 2003).…”