Translocation of green fluorescent protein to cyan

Authors: Wipa Chungjatupornchai Sirirat Faaroonsawat

Publish Date: 2009/05/02

Volume: 47, Issue: 2, Pages: 187-192

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Abstract

The translocation of proteins to cyanobacterial cell envelope is made complex by the presence of a highly differentiated membrane system To investigate the protein translocation in cyanobacterium Synechococcus PCC 7942 using the truncated ice nucleation protein InpNC from Pseudomonas syringae KCTC 1832 the green fluorescent protein GFP was fused in frame to the carboxylterminus of InpNC The fluorescence of GFP was found almost entirely as a halo in the outer regions of cells which appeared to correspond to the periplasm as demonstrated by confocal laser scanning microscopy however GFP was not displayed on the outermost cell surface Western blotting analysis revealed that InpNCGFP fusion protein was partially degraded The Nterminal domain of InpNC may be susceptible to protease attack the remaining Cterminal domain conjugated with GFP lost the ability to direct translocation across outer membrane and to act as a surface display motif The fluorescence intensity of cells with periplasmic GFP was approximately 6fold lower than that of cells with cytoplasmic GFP The successful translocation of the active GFP to the periplasm may provide a potential means to study the property of cyanobacterial periplasmic substances in response to environmental changes in a noninvasive manner

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