Lack of A-factor Production Induces the Expression of Nutrient Scavenging and Stress-related Proteins in Streptomyces griseus >

Zsuzsanna Birkó,Magdalena Swiatek,Emília Szájli,Katalin F Medzihradszky,Erik Vijgenboom,András Penyige,Judit Keserű,Gilles P Van Wezel,Sándor Biró

doi:10.1074/mcp.m900194-mcp200

Abstract

The small gamma-butyrolactone A-factor is an important autoregulatory signaling molecule for the soil-inhabiting streptomycetes. Starvation is a major trigger for development, and nutrients are provided by degradation of the vegetative mycelium via a process of programmed cell death, reusing proteins, nucleic acids, and cell wall material. The A-factor regulon includes many extracellular hydrolases. Here we show via proteomics analysis that many nutrient-scavenging and stress-related proteins were overexpressed in an A-factor non-producing mutant of Streptomyces griseus B-2682. Transcript analysis showed that this is primarily due to differential transcription of the target genes during early development. The targets include proteins relating to nutrient stress and environmental stress and an orthologue of the Bacillus sporulation control protein Spo0M. The enhanced expression of these proteins underlines the stress that is generated by the absence of A-factor. Wild-type developmental gene expression was restored to the A-factor non-producing mutant by the signaling protein Factor C in line with our earlier observation that Factor C triggers A-factor production.

Highlights

The small ␥-butyrolactone A-factor is an important autoregulatory signaling molecule for the soil-inhabiting streptomycetes
A-factordeficient mutants are neither able to sporulate nor able to produce antibiotics. Another interesting autoregulator is the secreted signaling protein Factor C originally isolated from the culture fluid of “S. griseus 45H” [11], which was recently shown to be identical to a laboratory strain known as Streptomyces flavofungini, itself a member of the Streptomyces albidoflavus species group [12]
We show that the bald A-factor non-producing mutant (AFN)1 overexpressed several ABC transporter solute-binding proteins and stress response proteins compared with the wild-type S. griseus B-2682 strain or with the facC transformant of the AFN in an effort to supply the cells with nutrients

Summary

Introduction

The small ␥-butyrolactone A-factor is an important autoregulatory signaling molecule for the soil-inhabiting streptomycetes. We show that the bald A-factor non-producing mutant (AFN)1 overexpressed several ABC transporter solute-binding proteins and stress response proteins compared with the wild-type S. griseus B-2682 strain or with the facC transformant of the AFN in an effort to supply the cells with nutrients. Tryptic digests were extracted into 1% formic acid, 50% ACN, 1 The abbreviations used are: AFN, A-factor non-producing mutant; ABC, ATP-binding cassette; 2D, two-dimensional; NCBI, National Center for Biotechnology Information; SGR, S. griseus; ID, identification number; SCO, S. coelicolor; NRRL, Northern Regional Research Laboratory (National Center for Agricultural Utilization Research).

Results

Conclusion