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Vainonen, Julia P
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Publications (6 of 6) Show all publications
Turkina, M. V., Blanco-Rivero, A., Vainonen, J. P., Vener, A. V. & Villarejo, A. (2006). CO2 limitation induces specific redox-dependent protein phosphorylation in Chlamydomonas reinhardtii. Proteomics, 6(9), 2693-2704
Open this publication in new window or tab >>CO2 limitation induces specific redox-dependent protein phosphorylation in Chlamydomonas reinhardtii
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2006 (English)In: Proteomics, ISSN 1615-9853, Vol. 6, no 9, p. 2693-2704Article in journal (Refereed) Published
Abstract [en]

Acclimation of the green alga Chlamydomonas reinhardtii to limiting environmental CO2 induced specific protein phosphorylation at the surface of photosynthetic thylakoid membranes. Four phosphopeptides were identified and sequenced by nanospray quadrupole TOF MS from the cells acclimating to limiting CO2. One phosphopeptide originated from a protein that has not been annotated. We found that this unknown expressed protein (UEP) was encoded in the genome of C. reinhardtii. Three other phosphorylated peptides belonged to Lci5 protein encoded by the low-CO2-inducible gene 5 (lci5). The phosphorylation sites were mapped in the tandem repeats of Lci5 ensuring phosphorylation of four serine and three threonine residues in the protein. Immunoblotting with Lci5-specific antibodies revealed that Lci5 was localized in chloroplast and confined to the stromal side of the thylakoid membranes. Phosphorylation of Lci5 and UEP occurred strictly at limiting CO2; it required reduction of electron carriers in the thylakoid membrane, but was not induced by light. Both proteins were phosphorylated in the low-CO2-exposed algal mutant deficient in the light-activated protein kinase Stt7. Phosphorylation of previously unknown basic proteins UEP and Lci5 by specific redox-dependent protein kinase(s) in the photosynthetic membranes reveals the early response of green algae to limitation in the environmental inorganic carbon.

Keywords
Amino acid sequencing, Chlamydomonas reinhardtii, CO2 limitation, Mass spectrometry, Protein phosphorylation
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-12927 (URN)10.1002/pmic.200500461 (DOI)
Available from: 2008-02-06 Created: 2008-02-06 Last updated: 2009-06-05
Tikkanen, M., Piippo, M., Suorsa, M., Sirpiö, S., Mulo, P., Vainonen, J., . . . Aro, E.-M. (2006). State transitions revisited - A buffering system for dynamic low light acclimation of Arabidopsis. Plant Molecular Biology, 62( 4-5), 779-793
Open this publication in new window or tab >>State transitions revisited - A buffering system for dynamic low light acclimation of Arabidopsis
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2006 (English)In: Plant Molecular Biology, ISSN 0167-4412, E-ISSN 1573-5028, Vol. 62, no 4-5, p. 779-793Article in journal (Refereed) Published
Abstract [en]

The mobile part of the light-harvesting chlorophyll (chl) a/b protein complex (LHCII), composed of the Lhcb1 and Lhcb2 proteins, is the basic unit of chloroplast state transitions-the short term tuning system in balancing the excitation energy between Photosystem (PS) II and PSI. State transitions are catalysed by the thylakoid associated STN7 kinase, and we show here that besides the phosphorylation of the Lhcb1 and Lhcb2 proteins, also the phosphorylation of Lhcb4.2 (CP29) is under the control of the STN7 kinase. Upon growth of Arabidopsis WT and stn7 mutant plants under low and moderate light conditions, the WT plants favoured state 2 whereas stn7 was locked in state 1. The lack of the STN7 kinase and state transitions in stn7 also modified the thylakoid protein contents upon long-term low light acclimation resulting, for example, in low Lhcb1 and in elevated Lhca1 and Lhca2 protein amounts as compared to WT. Adjustments of thylakoid protein contents probably occurred at post-transcriptional level since the DNA microarray experiments from each growth condition did not reveal any significant differences between stn7 and WT transcriptomes. The resulting high Lhcb2/Lhcb1 ratio in stn7 upon growth at low light was accompanied by lower capacity for NPQ than in WT. On the contrary, higher amounts of PsbS in stn7 under moderate and high light growth conditions resulted in higher NPQ compared to WT and consequently also in a protection of PSII against photoinhibition. STN7 kinase and the state transitions are suggested to have a physiological significance for dynamic acclimation to low but fluctuating growth light conditions. They are shown to function as a buffering system upon short high light illumination peaks by shifting the thylakoids from state 2 to state 1 and thereby down regulating the induction of stress-responsive genes, a likely result from transient over-reduction of PSI acceptors. © 2006 Springer Science+Business Media B.V.

National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-35819 (URN)10.1007/s11103-006-9044-8 (DOI)28648 (Local ID)28648 (Archive number)28648 (OAI)
Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2017-12-13
Khrouchtchova, A., Hansson, M., Paakkarinen, V., Vainonen, J. P., Zhang, S., Jensen, P. E., . . . Haldrup, A. (2005). A previosly found thylakoid membrane protein of 14 kDa (TMP14) is a novel subunit of photosystem I and is designated PSI-P. FEBS Letters, 579(21), 4808-4812
Open this publication in new window or tab >>A previosly found thylakoid membrane protein of 14 kDa (TMP14) is a novel subunit of photosystem I and is designated PSI-P
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2005 (English)In: FEBS Letters, ISSN 0014-5793, Vol. 579, no 21, p. 4808-4812Article in journal (Refereed) Published
Abstract [en]

We show that the thylakoid membrane phosphoprotein TMP14 is a novel subunit of plant photosystem I (PSI). Blue native/SDS–PAGE and sucrose gradient fractionation demonstrated the association of the protein exclusively with PSI. We designate the protein PSI-P. The presence of PSI-P subunit in Arabidopsis mutants lacking other PSI subunits was analyzed and suggested a location in the proximity of PSI-L, -H and -O subunits. The PSI-P protein was not differentially phosphorylated in state 1 and state 2.

Keywords
Photosystem I; Protein phosphorylation; State transitions; Thylakoids; Arabidopsis
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-13860 (URN)10.1016/j.febslet.2005.07.061 (DOI)
Available from: 2006-09-07 Created: 2006-09-07
Vainonen, J. P., Hansson, M. & Vener, A. V. (2005). STN8 protein kinase in Arabidopsis thaliana is specific in phosphorylation of photosystem II core proteins. Journal of Biological Chemistry, 280(39), 33679-33686
Open this publication in new window or tab >>STN8 protein kinase in Arabidopsis thaliana is specific in phosphorylation of photosystem II core proteins
2005 (English)In: Journal of Biological Chemistry, ISSN 0021-9258, Vol. 280, no 39, p. 33679-33686Article in journal (Refereed) Published
Abstract [en]

Combination of reversed genetics with analyses of in vivo protein phosphorylation in Arabidopsis thaliana revealed that STN8 protein kinase is specific in phosphorylation of N-terminal threonine residues in D1, D2, and CP43 proteins, and Thr-4 in the PsbH protein of photosystem II. Phosphorylation of D1, D2, and CP43 in the light-exposed leaves of two Arabidopsis lines with T-DNA insertions in the stn8 gene was found significantly reduced in the assays with anti-phosphothreonine antibodies. Protein phosphorylation in each of the mutants was quantified comparatively to the wild type by mass spectrometric analyses of phosphopeptides released from the photosynthetic membranes and differentially labeled with stable isotopes. The lack of STN8 caused 50-60% reduction in D1 and D2 phosphorylation, but did not change the phosphorylation level of two peptides that could correspond to light-harvesting proteins encoded by seven different genes in Arabidopsis. Phosphorylation of the PsbH protein at Thr-4 was completely abolished in the plants lacking STN8. Phosphorylation of Thr-4 in the wild type required both light and prior phosphorylation at Thr-2, indicating that STN8 is a light-activated kinase that phosphorylates Thr-4 only after another kinase phosphorylates Thr-2. Analysis of the STN8 catalytic domain suggests that selectivity of STN8 in phosphorylation of the very N-terminal residues in D1, D2, and CP43, and Thr-4 in PsbH pre-phosphorylated at Thr-2 may be explained by the long loops obstructing entrance into the kinase active site and seven additional basic residues in the vicinity of the catalytic site, as compared with the homologous STN7 kinase responsible for phosphorylation of light-harvesting proteins.

National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-13863 (URN)10.1074/jbc.M505729200 (DOI)
Available from: 2006-09-07 Created: 2006-09-07 Last updated: 2009-06-08
Vainonen, J. P., Aboulaich, N., Turkina, M. V., Strålfors, P. & Vener, A. V. (2004). N-terminal processing and modifications of caveolin-1 in caveolae from human adipocytes. Biochemical and Biophysical Research Communications - BBRC, 320(2), 480-486
Open this publication in new window or tab >>N-terminal processing and modifications of caveolin-1 in caveolae from human adipocytes
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2004 (English)In: Biochemical and Biophysical Research Communications - BBRC, ISSN 0006-291X, E-ISSN 1090-2104, Vol. 320, no 2, p. 480-486Article in journal (Refereed) Published
Abstract [en]

Caveolin, the principal structural protein of caveolae membrane domains, has a cytosol-exposed N-terminal part that was cleaved off by trypsin treatment of caveolae vesicles isolated from primary human adipocytes. Sequencing of the released tryptic peptides by nanospray quadrupole time-of-flight mass spectrometry revealed that both caveolin-1alpha and caveolin-1beta were processed by excision of the starting methionines. The N-terminus of the mature caveolin-1alpha was acetylated, while caveolin-1beta was found in acetylated as well as in non-acetylated forms. Fractional phosphorylation of serine-36 in the mature caveolin-1alpha and of the homologous serine-5 in caveolin-1beta was identified. This is the first experimental evidence for in vivo phosphorylation of caveolin-1 at the consensus site for phosphorylation by protein kinase C. The phosphorylation was found in both the acetylated and non-acetylated variants of caveolin-1beta. This variability in modifications is consistent with critical involvement of the N-terminal domain of caveolin in the regulation of caveolae.

Keywords
Human adipocyte, Caveolin-1; Caveolae, Protein phosphorylation, N-terminal acetylation, Mass spectrometry
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-19146 (URN)10.1016/j.bbrc.2004.05.196 (DOI)15219854 (PubMedID)
Available from: 2009-06-12 Created: 2009-06-12 Last updated: 2017-12-13Bibliographically approved
Aboulaich, N., Vainonen, J. P., Strålfors, P. & Vener, A. V. (2004). Vectorial proteomics reveal targeting, phosphorylation and specific fragmentation of polymerase I and transcript release factor (PTRF) at the surface of caveolae in human adipocytes. The Biochemical journal, 383(Pt 2), 237-248
Open this publication in new window or tab >>Vectorial proteomics reveal targeting, phosphorylation and specific fragmentation of polymerase I and transcript release factor (PTRF) at the surface of caveolae in human adipocytes
2004 (English)In: The Biochemical journal, ISSN 1470-8728, Vol. 383, no Pt 2, p. 237-248Article in journal (Refereed) Published
Abstract [en]

Caveolae, the specialized invaginations of plasma membranes, formed sealed vesicles with outwards-orientated cytosolic surface after isolation from primary human adipocytes. This morphology allowed differential, vectorial identification of proteins at the opposite membrane surfaces by proteolysis and MS. Extracellular-exposed caveolae-specific proteins CD36 and copper-containing amine oxidase were concealed inside the vesicles and resisted trypsin treatment. The cytosol-orientated caveolins were efficiently digested by trypsin, producing peptides amenable to direct MS sequencing. Isolation of peripheral proteins associated with the cytosolic surface of caveolae revealed a set of proteins that contained nuclear localization signals, leucine-zipper domains and PEST (amino acid sequence enriched in proline, glutamic acid, serine and threonine) domains implicated in regulation by proteolysis. In particular, PTRF (polymerase I and transcript release factor) was found as a major caveolae-associated protein and its co-localization with caveolin was confirmed by immunofluorescence confocal microscopy. PTRF was present at the surface of caveolae in the intact form and in five different truncated forms. Peptides (44 and 45 amino acids long) comprising both the PEST domains were sequenced by nanospray-quadrupole-time-of-flight MS from the full-length PTRF, but were not found in the truncated forms of the protein. Two endogenous cleavage sites corresponding to calpain specificity were identified in PTRF; one of them was in a PEST domain. Both cleavage sites were flanked by mono- or diphosphorylated sequences. The phosphorylation sites were localized to Ser-36, Ser-40, Ser-365 and Ser-366 in PTRF. Caveolae of human adipocytes are proposed to function in targeting, relocation and proteolytic control of PTRF and other PEST-domain-containing signalling proteins.

Keywords
Caveolae, human adipocyte, MS, PEST sequence, polymerase I and transcript release factor (PTRF), proteolysis
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-19145 (URN)10.1042/BJ20040647 (DOI)15242332 (PubMedID)
Available from: 2009-06-12 Created: 2009-06-12 Last updated: 2009-06-12Bibliographically approved
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