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Journal of Bacteriology, December 2002, p. 6417-6423, Vol. 184, No. 23
0021-9193/02/$04.00+0     DOI: 10.1128/JB.184.23.6417-6423.2002
Copyright © 2002, American Society for Microbiology. All Rights Reserved.

The rpoZ Gene, Encoding the RNA Polymerase Omega Subunit, Is Required for Antibiotic Production and Morphological Differentiation in Streptomyces kasugaensis

Ikuo Kojima,^1* Kano Kasuga,¹ Masayuki Kobayashi,¹ Akira Fukasawa,^2, Satoshi Mizuno,^2, Akira Arisawa,³ and Hisayoshi Akagawa²

Department of Biotechnology, Faculty of Bioresource Sciences, Akita Prefectural University, Akita 010-0195,¹ Department of Bioactive Molecules, National Institute of Infectious Diseases, Tokyo 162-8640,² Bioresource Laboratories, MERCIAN Corporation, Fujisawa 251-0057, Japan³

Received 23 May 2002/ Accepted 21 August 2002

The occurrence of pleiotropic mutants that are defective in both antibiotic production and aerial mycelium formation is peculiar to streptomycetes. Pleiotropic mutant KSB was isolated from wild-type Streptomyces kasugaensis A1R6, which produces kasugamycin, an antifungal aminoglycoside antibiotic. A 9.3-kb DNA fragment was cloned from the chromosomal DNA of strain A1R6 by complementary restoration of kasugamycin production and aerial hypha formation to mutant KSB. Complementation experiments with deletion plasmids and subsequent DNA analysis indicated that orf5, encoding 90 amino acids, was responsible for the restoration. A protein homology search revealed that orf5 was a homolog of rpoZ, the gene that is known to encode RNA polymerase subunit omega (), thus leading to the conclusion that orf5 was rpoZ in S. kasugaensis. The pleiotropy of mutant KSB was attributed to a 2-bp frameshift deletion in the rpoZ region of mutant KSB, which probably resulted in a truncated, incomplete of 47 amino acids. Furthermore, rpoZ-disrupted mutant R6D4 obtained from strain A1R6 by insertion of Tn5 aphII into the middle of the rpoZ-coding region produced neither kasugamycin nor aerial mycelia, similar to mutant KSB. When rpoZ of S. kasugaensis and Streptomyces coelicolor, whose deduced products differed in the sixth amino acid residue, were introduced into mutant R6D4 via a plasmid, both transformants produced kasugamycin and aerial hyphae without significant differences. This study established that rpoZ is required for kasugamycin production and aerial mycelium formation in S. kasugaensis and responsible for pleiotropy.

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* Corresponding author. Mailing address: Department of Biotechnology, Faculty of Bioresource Sciences, Akita Prefectural University, 241-7 Shimo-shinjo, Nakano, Akita 010-0195, Japan. Phone: 81 (18) 872-1595. Fax: 81 (18) 872-1676. E-mail: kojima{at}akita-pu.ac.jp.

Present address: Keyiyo Co., Ltd., Higashiyatsushiro 405-0073, Japan.

National Center for Safety Evaluation of Drugs, Beijing 100176, China.

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Journal of Bacteriology, December 2002, p. 6417-6423, Vol. 184, No. 23
0021-9193/02/$04.00+0     DOI: 10.1128/JB.184.23.6417-6423.2002
Copyright © 2002, American Society for Microbiology. All Rights Reserved.

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