Vipp1 and PspA

Abstract

The Vesicle Inducing Protein in Plastids 1 (Vipp1) was suggested to be involved in thylakoid mem- brane formation in both chloroplasts and cyanobacteria. The protein shows sequence homology to the Phage Shock Protein A (PspA) from bacteria, and both proteins have similar secondary structures. 2D-structures of PspA and of Vipp1 have been determined by elec- tron microscopy in the recent years. Both PspA and Vipp1 form large homooligo- meric rings with high molecular masses but their ring dimensions differ signifi- cantly. Furthermore, Vipp1 forms rings with different rotational symmetries whereas PspA appears to form rings with singular rotational symmetry. In this article addendum we compare the struc- tures of PspA and Vipp1. Furthermore, we suggest a spatial structural model of the observed Vipp1 rings.