| 1. |
- Ansell, R, et al.
(författare)
-
The two isoenzymes for yeast NAD+-dependent glycerol 3-phosphate dehydrogenase encoded by GPD1 and GPD2 have distinct roles in osmoadaptation and redox regulation.
- 1997
-
Ingår i: The EMBO journal. - : Wiley. - 0261-4189 .- 1460-2075. ; 16:9, s. 2179-87
-
Tidskriftsartikel (refereegranskat)abstract
- The two homologous genes GPD1 and GPD2 encode the isoenzymes of NAD-dependent glycerol 3-phosphate dehydrogenase in the yeast Saccharomyces cerevisiae. Previous studies showed that GPD1 plays a role in osmoadaptation since its expression is induced by osmotic stress and gpd1 delta mutants are osmosensitive. Here we report that GPD2 has an entirely different physiological role. Expression of GPD2 is not affected by changes in external osmolarity, but is stimulated by anoxic conditions. Mutants lacking GPD2 show poor growth under anaerobic conditions. Mutants deleted for both GPD1 and GPD2 do not produce detectable glycerol, are highly osmosensitive and fail to grow under anoxic conditions. This growth inhibition, which is accompanied by a strong intracellular accumulation of NADH, is relieved by external addition of acetaldehyde, an effective oxidizer of NADH. Thus, glycerol formation is strictly required as a redox sink for excess cytosolic NADH during anaerobic metabolism. The anaerobic induction of GPD2 is independent of the HOG pathway which controls the osmotic induction of GPD1. Expression of GPD2 is also unaffected by ROX1 and ROX3, encoding putative regulators of hypoxic and stress-controlled gene expression. In addition, GPD2 is induced under aerobic conditions by the addition of bisulfite which causes NADH accumulation by inhibiting the final, reductive step in ethanol fermentation and this induction is reversed by addition of acetaldehyde. We conclude that expression of GPD2 is controlled by a novel, oxygen-independent, signalling pathway which is required to regulate metabolism under anoxic conditions.
|
|
| 2. |
|
|
| 3. |
- Bohmert, K., et al.
(författare)
-
AGO1 defines a novel locus of Arabidopsis controlling leaf development
- 1998
-
Ingår i: EMBO Journal. - : Wiley. - 0261-4189 .- 1460-2075. ; 17:1, s. 170-180
-
Tidskriftsartikel (refereegranskat)abstract
- An allelic series of the novel argonaute mutant (ago1-1 to ago1-6) of the herbaceous plant Arabidopsis thaliana has been isolated, The ago1 mutation pleotropically affects general plant architecture, The apical shoot meristem generates rosette leaves and a single stem, but axillary meristems rarely develop, Rosette leaves lack a leaf blade but still show adaxial/abaxial differentiation, Instead of cauline leaves, filamentous structures without adaxial/abaxial differentiation develop along the stem and an abnormal inflorescence bearing infertile flowers with filamentous organs is produced, Two independent T-DNA insertions into the AGO1 locus led to the isolation of two corresponding genomic sequences as well as a complete cDNA. The AGO1 locus was mapped close to the marker mi291a on chromosome 1. Antisense expression of the cDNA resulted in a partial mutant phenotype, Sense expression caused some transgenic lines to develop goblet-like leaves and petals, The cDNA encodes a putative 115 kDa protein with sequence similarity tea translation products of a novel gene family present in nematodes as,yell as humans, No specific function has been assigned to these genes, Similar proteins are not encoded by the genomes of yeast or bacteria, suggesting that AGOI belongs to a novel class of genes with a function specific to multicellular organisms.
|
|
| 4. |
|
|
| 5. |
- CAMPBELL, D, et al.
(författare)
-
ELECTRON-TRANSPORT REGULATES EXCHANGE OF 2 FORMS OF PHOTOSYSTEM-II D1 PROTEIN IN THE CYANOBACTERIUM SYNECHOCOCCUS
- 1995
-
Ingår i: EMBO Journal. - 0261-4189 .- 1460-2075. ; 14:22, s. 5457-5466
-
Tidskriftsartikel (refereegranskat)abstract
- Synechococcus sp, PCC 7942 modulates photosynthetic function by transiently replacing the constitutive D1 photosystem II protein, D1:1, with an alternate form, D1:2, to help counteract photoinhibition under excess light, We show that a temperature drop from 37 to 25 degrees C also drives D1:1/D1:2 exchange under constant, moderate light, Chilling or light-induced D1 exchange results from rapid loss of psbAI message coding for D1:1 and accumulation of psbAII and psbAIII messages coding for D1:2, During chilling, a large pool of a novel form, D1:2*, transiently accumulates, distinguishable from normal D1 by an increase in apparent molecular mass, D1:* is not phosphorylated and is probably a functionally inactive, incompletely processed precursor, After acclimation to 25 degrees C, D1:2* disappears and D1:1 again predominates, although substantial D1:2 remains, Partial inhibition of electron transport under constant, moderate light also triggers the D1 exchange process, These treatments all increase excitation pressure on photosystem II relative to electron transport, Therefore, information from photosynthetic electron transport regulates D1 exchange without any requirement for a change in light intensity or quality, possibly via a redox sensing mechanism proximal to photosystem II.
|
|
| 6. |
|
|
| 7. |
|
|
| 8. |
|
|
| 9. |
|
|
| 10. |
|
|
