FIG. 4.

Transcriptional analysis of the lcp gene region. (a) Molecular organization of the 8-kbp Sau3A fragment from plasmid pR harboring lcp and adjacent genes. nakg encodes N-acetylglutamate kinase, lcp encodes latex-clearing protein (putative secreted protein), oxiB encodes oxidoreductase β-subunit, oxiA encodes oxidoreductase α-subunit, eno encodes enolase 2-phosphoglycerate dehydratase, and mem encodes a putative membrane transporter. The lines with numbers or letters represent the RT-PCR products obtained with mRNA from Streptomyces sp. strain K30; the numbers indicate the specific cDNA transcription products in the gel, and the letters indicate products of the other RT-PCRs. (b and c) Transcription analysis of the lcp region in Streptomyces sp. strain K30. Expression of lcp was analyzed by RT-PCR performed with samples containing total RNA isolated from cells in the logarithmic growth phase. The resulting PCR products were separated by agarose gel electrophoresis and stained with ethidium bromide, and negative images are shown. Cells were grown in MSM with either 0.5% (wt/vol) poly(cis-1,4-isoprene) (b) or 0.5% (wt/vol) glucose (c) as the carbon source. Lanes 1′, 2′, 3′, 4′, and 5′ contained the controls used to detect DNA contamination, whereas lanes 1, 2, 3, 4 and 5 contained the RT-PCR assay mixtures. A 100-bp DNA ladder (MBI Fermentas, Germany) (lanes M) was used as a molecular weight standard. Transcription of lcp (panel b, lane 1), oxiB (panel b, lane 2), oxiA (panel b, lane 3), Lcp into the OxiB PCR product (panel b, lane 4), and OxiB into the OxiA PCR product (panel b, lane5) was strongly induced in the presence of natural or synthetic rubber poly(cis-1,4-isoprene), while in the presence of glucose only a faint RT-PCR product of lcp (panel c, lane 1) was detected; RT-PCR products of oxiB and oxiA could not be detected at all.