Secretion by numbers: Protein traffic in prokaryotes

Abstract

Almost all aspects of protein traffic in bacteria were covered at the ASM-FEMS meeting on the topic in Iraklio, Crete in May 2006. The studies presented ranged from mechanistic analysis of specific events leading proteins to their final destinations to the physiological roles of the targeted proteins. Among the highlights from the meeting that are reviewed here are the molecular dynamics of SecA protein, membrane protein insertion, type III secretion needles and chaperones, type IV secretion, the two partner and autosecretion systems, the 'secretion competent state', and the recently discovered type VI secretion system.

Fig. 1

Lipase of Burholderia glumae (blue) with its specific chaperone (Lif) wrapped around it to form a large folding platform (Pauwels et al., 2006).

Fig. 2

Cross sections of the proposed structure of the T3SS needle complex (brown), based on the crystal structure of MxiH modelled into a three-dimensional EM reconstruction of the needle with an helix (blue) modelled at its centre to show that the dimensions of the central channel cannot accommodate more than simple secondary structures in proteins (needle subunits, translocator proteins, effectors) that move through it. (Figure generously supplied by Janet Deane).