Identification and partial characterization of Rhizopus nigricans Gβ proteins and their expression in the presence of progesterone

• Published in: The Journal of steroid biochemistry and molecular biology 2012-03, Vol.129 (1-2), p.99-105
• Main Authors: Jeraj, Nataša, Stilla, Annalisa, Petrič, Špela, Di Girolamo, Maria, Črešnar, Bronislava, Lenasi, Helena
• Format: Article
• Language: English
• Subjects: ADP-ribosylation; Amino Acid Sequence; cDNA; Fungal Proteins - biosynthesis; Fungal Proteins - isolation & purification; Fungal Proteins - metabolism; Gene expression; Gβ protein; Heterotrimeric GTP-Binding Proteins - biosynthesis; Heterotrimeric GTP-Binding Proteins - isolation & purification; Heterotrimeric GTP-Binding Proteins - metabolism; Molecular Sequence Data; NAD - metabolism; Progesterone; Progesterone - pharmacology; Protein Subunits - biosynthesis; Protein Subunits - isolation & purification; Protein Subunits - metabolism; Rhizopus - drug effects; Rhizopus - metabolism; Sequence Alignment; Zygomycete Rhizopus nigricans
• ISSN: 0960-0760; 1879-1220
• DOI: 10.1016/j.jsbmb.2010.12.015

The mammalian steroid hormone progesterone actuates a signalling pathway in the zygomycete Rhizopus nigricans which includes heterotrimeric G proteins. To investigate the possibility that the Gβ subunit of these proteins is involved in the signalling, a cDNA library from R. nigricans exposed to progesterone was prepared and a sequence coding for a Gβ subunit was searched for. Using degenerate primers, two sequences, RnGPB1 and RnGPB2, were identified that exhibited a high degree of identity with those for Gβ from other filamentous fungi, but not from yeast. The presence of more than one Gβ subunit is very rare among the fungi, and it has been to date reported only for Rhizopus oryzae. We have shown that progesterone increases the expression of RnGPB1, but has no influence on the expression of RnGPB2. Therefore, our studies imply the involvement of Gβ subunit 1 in the response of R. nigricans to progesterone. Moreover, the Gβ subunit is subjected to endogenous ADP-ribosylation in the presence of NAD, which could be important in some, as yet unknown, cell process. Article from a special issue on steroids and microorganisms.