Biochemical analysis of three putative KaiC clock proteins from Synechocystis sp. PCC 6803 suggests their functional divergence.

Cyanobacteria have been shown to have a circadian clock system that consists mainly of three protein components: KaiA, KaiB and KaiC. This system is well understood in the cyanobacterium Synechococcus elongatus PCC 7942, for which robust circadian oscillations have been shown. Like many other cyanobacteria, the chromosome of the model cyanobacterium Synechocystis sp.

Genome streamlining results in loss of robustness of the circadian clock in the marine cyanobacterium Prochlorococcus marinus PCC 9511.

The core oscillator of the circadian clock in cyanobacteria consists of 3 proteins, KaiA, KaiB, and KaiC. All 3 have previously been shown to be essential for clock function. Accordingly, most cyanobacteria possess at least 1 copy of each kai gene.

Two distinct types of 6S RNA in Prochlorococcus.

Different forms of the 6S non-coding RNA (ncRNA) exist in enterobacteria and in B. subtilis but there is only limited information about this RNA from other groups of bacteria. Prochlorococcus is an oceanic, ecologically important, cyanobacterium.

UV-induced phycobilisome dismantling in the marine picocyanobacterium Synechococcus sp. WH8102.

The marine picocyanobacterium Synechococcus sp. WH8102 was submitted to ultraviolet (UV-A and B) radiations and the effects of this stress on reaction center II and phycobilisome integrity were studied using a combination of biochemical, biophysical and molecular biology techniques. Under the UV conditions that were applied (4.

Biochemical bases of type IV chromatic adaptation in marine Synechococcus spp.

Chromatic adaptation (CA) in cyanobacteria has provided a model system for the study of the environmental control of photophysiology for several decades. All forms of CA that have been examined so far (types II and III) involve changes in the relative contents of phycoerythrin (PE) and/or phycocyanin when cells are shifted from red to green light and vice versa. However, the chromophore compositions of these polypeptides are not altered.

Cell cycle control by oscillating regulatory proteins in Caulobacter crescentus.

Significant strides have been made in recent years towards understanding the molecular basis of cell cycle progression in the model bacterium Caulobacter crescentus. At the heart of cell cycle regulation is a multicomponent transcriptional feedback loop, governing the production of successive regulatory waves or pulses of at least three master regulatory proteins. These oscillating master regulators direct the execution of phase-specific events and, importantly, through intrinsic genetic switches not only determine the length of a given phase, but also provide the driving force that catapults the cell into the next stage of the cell cycle.

Oscillating global regulators control the genetic circuit driving a bacterial cell cycle.

A newly identified cell-cycle master regulator protein, GcrA, together with the CtrA master regulator, are key components of a genetic circuit that drives cell-cycle progression and asymmetric polar morphogenesis in Caulobacter crescentus. The circuit drives out-of-phase temporal and spatial oscillation of GcrA and CtrA concentrations, producing time- and space-dependent transcriptional regulation of modular functions that implement cell-cycle processes. The CtrA/GcrA regulatory circuit controls expression of polar differentiation factors and the timing of DNA replication.

Synchronized expression of ftsZ in natural Prochlorococcus populations of the Red Sea.

The expression of ftsZ, encoding the initiating protein of the prokaryotic cell division was analysed in natural Prochlorococcus populations in the Gulf of Aqaba, northern Red Sea. During the seasonal Prochlorococcus bloom in September 2000, picoplankton was collected from the deep chlorophyll maximum (DCM) at 2-4 h intervals over 3 consecutive days. Flow cytometric measurements as well as DNA sequence analyses showed that Prochlorococcus was the dominant photosynthetic organism.