Molecular and Cellular Biology, June 2001, p. 4075-4088, Vol. 21, No. 12
Laboratorium für Mikrobiologie,
Philipps-Universität Marburg and Max-Planck-Institut
für Terrestrische Mikrobiologie, D-35043 Marburg, Germany
Received 10 November 2000/Returned for modification 28 December
2000/Accepted 5 March 2001
The filamentous fungus Aspergillus nidulans
reproduces asexually through the formation of spores on a multicellular
aerial structure, called a conidiophore. A key regulator of asexual
development is the TFIIIA-type zinc finger containing transcriptional
activator Bristle (BRLA). Besides BRLA, the
transcription factor ABAA, which is located downstream of BRLA in the
developmental regulation cascade, is necessary to direct later gene
expression during sporulation. We isolated a new developmental mutant
and identified a leaky brlA mutation and the mutated
Saccharomyces cerevisiae cyclin homologue
pclA, both contributing to the developmental phenotype of the mutant. pclA was found to be 10-fold
transcriptionally upregulated during conidiation, and a
pclA deletion strain was reduced three- to fivefold in
production of conidia. Expression of pclA was strongly
induced by ectopic expression of brlA or abaA under conidiation-suppressing conditions,
indicating a direct role for brlA and
abaA in pclA regulation. PCLA is
homologous to yeast Pcl cyclins, which interact with the Pho85
cyclin-dependent kinase. Although interaction with a PSTAIRE kinase was
shown in vivo, PCLA function during sporulation was independent of the A. nidulans Pho85 homologue PHOA. Besides the
developmental regulation, pclA expression was cell cycle
dependent with peak transcript levels in S phase. Our findings suggest
a role for PCLA in mediating cell cycle events during late stages of sporulation.
0270-7306/01/$04.00+0 DOI: 10.1128/MCB.21.12.4075-4088.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.
A Pcl-Like Cyclin of Aspergillus nidulans Is
Transcriptionally Activated by Developmental Regulators and Is Involved
in Sporulation
*
Laboratorium für Mikrobiologie,
Philipps-Universität Marburg and Max-Planck-Insitut für
Terrestrische Mikrobiologie, Karl-von-Frisch-Str., D-35043 Marburg,
Germany. Phone: 49-6421-178-330. Fax: 49-6421-178-309. E-mail:
FischerR{at}mailer.uni-marburg.de.
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