Novel dynamics of FtsZ ring before plastid abscission

Abstract

Plastids were derived from free-living cyanobacterium ancestors that were engulfed by a primary non-photosynthetic eukaryotic host cell and subsequently evolved into plastids. Consistent with their bacterial origin, plastids use the bacterial FtsZ ring, the gene of which was transferred to the host eukaryotic nucleus over evolutionary time. However, recent genome sequencing projects show that most of the other proteins once involved in bacterial division have been lost. Here we show, highly sensitive immunofluorescence analysis using plastid FtsZ antiserum revealed that plastid FtsZ forms two types of ring structures during plastid division: (i) the 1st FtsZ ring is formed at the division site to constitute the foundation of the plastid division machinery and (ii) the 2nd FtsZ ring is formed at a right angle with the 1st FtsZ ring. One notable point is that the 2nd FtsZ ring disappears at the end of plastid division. This result suggests that the nuclear encoded plastid FtsZ may function in daughter plastids, in addition to foundation of the plastid division machinery. © 2008 The Japan Mendel Society.