Kümpel, C.; Grein, F.; Dahl, C. Fluorescence Microscopy Study of the Intracellular Sulfur Globule Protein SgpD in the Purple Sulfur Bacterium Allochromatium vinosum. Microorganisms2023, 11, 1792.
Kümpel, C.; Grein, F.; Dahl, C. Fluorescence Microscopy Study of the Intracellular Sulfur Globule Protein SgpD in the Purple Sulfur Bacterium Allochromatium vinosum. Microorganisms 2023, 11, 1792.
Kümpel, C.; Grein, F.; Dahl, C. Fluorescence Microscopy Study of the Intracellular Sulfur Globule Protein SgpD in the Purple Sulfur Bacterium Allochromatium vinosum. Microorganisms2023, 11, 1792.
Kümpel, C.; Grein, F.; Dahl, C. Fluorescence Microscopy Study of the Intracellular Sulfur Globule Protein SgpD in the Purple Sulfur Bacterium Allochromatium vinosum. Microorganisms 2023, 11, 1792.
Abstract
When oxidizing reduced sulfur compounds, the phototrophic sulfur bacterium Allochromatium vinosum forms spectacular sulfur globules as obligatory intracellular – but extracytoplasmic – intermediates. The globule envelope consists of three extremely hydrophobic proteins: SgpA and SgpB are very similar and can functionally replace each other. SgpC is involved in the expansion of the sulfur globules. The presence of a fourth protein, SgpD, has been suggested by comparative transcriptomics and proteomics of enriched sulfur globules. Here, we investigated the in vivo function of SgpD by coupling its carboxy-terminus to mCherry. This fluorescent protein requires oxygen for chromophore maturation, but we were able to use it in anaerobically growing A. vinosum provided the cells were exposed to oxygen for one hour prior to imaging. While mCherry lacking a signal peptide resulted in low fluorescence evenly distributed throughout the cell, fusion with SgpD carrying its original Sec-dependent signal peptide targeted mCherry to the periplasm and co-localized it exactly with the highly light-refractive sulfur deposits seen in sulfide-fed A. vinosum cells. Insertional inactivation of the sgpD gene showed that the protein is not essential for the formation and degradation of sulfur globules.
Biology and Life Sciences, Immunology and Microbiology
Copyright:
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
