博士 / 國立臺灣師範大學 / 生物學系 / 84 / The prokaryote Synechococcus RF-1 exhibits circadian rhythms of
nitrogen
fixation and leucine uptake after being entrained in a diurnal
light/dark regimen. The rhythms can also be established by small
temperature changes, in either a raised- or a lowered-
temperature cycle, within the growth permissive range. At the
biochemical level, the synthesis of more than ten of its
polypeptides is known to become entrained to a circadian
oscillating pattern. One of the circadian oscillating
polypeptides, COP23, was found to be located in the membrane and
its rhythmic synthesis rate controlled at the transcription
level. In addition to the protein synthesis rate, the content of
COP23 also exhibited a circadian rhythm. Stability of COP23,
examined by 35S-Methionine pulse labeling, revealed that
it was relatively stable in an arrhythmic culture. However, the
exposure of Synechococcus RF-1 to light/dark regimen induced not
only a circadian synthesis rhythm, but also a
rapid protein degradation of COP23 at a defined period of
time. The induction of rapid protein degradation was prevented
by the presence of chloramphenicol. The gene encoding
the COP23 polypeptide has been cloned and sequenced.
The amino acid sequence derived from the open reading frame
revealed that a signal peptide (28 amino acids) does not appear
to be part of the mature COP23. We also cloned and
sequenced the nifHDK operon which contains 4.5Kb.
Transcription start of cop23 and nifHDK operon were determined
by primer extension. The 5'' upstream of cop23 is
1.8Kb. It contains multiple repeats of two palindrome
sequences (GGCGATCGCC; TTATTAATAA) and an AT-rich region.
Comparison of the structure of the upstream of cop23 and nifHDK
does not reveal significant similarity.
| Identifer | oai:union.ndltd.org:TW/084NTNU0112001 |
| Date | January 1996 |
| Creators | Chen, Horng-Ming, 陳弘民 |
| Contributors | Chien Chiu-Yuan, Huang Tan-Chi, 簡秋源, 黃檀溪 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 2 |
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