Immunolocalization of NblA, a protein involved in phycobilisome turnover, during heterocyst differentiation in cyanobacteria

Alda, Jesús A. G. Ochoa de; Lichtlé, Christiane; Thomas, Jean‐Claude; Houmard, Jean

doi:10.1099/mic.0.26992-0

Cited by 11 publications

(13 citation statements)

References 28 publications

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“…The designation, NblA, reflects the 'nonbleaching' phenotype of the knockout-mutant, which remains blue-green under conditions that trigger phycobilisome degradation, in contrast with the wild type that turns yellowish or bleaches. Orthologs of NblA of S. elongatus (proteins of~6-7 kDa) have been identified in a variety of cyanobacteria and red algae (Baier et al, 2001(Baier et al, , 2004Richaud et al, 2001;Li and Sherman, 2002;Luque et al, 2003;de Alda et al, 2004;Kawakami et al, 2009). Transcription of nblA, which is induced by specific environmental cues, is subject to complex and tight regulation (Schwarz and Grossman, 1998;Sauer et al, 1999;Luque et al, 2001;van Waasbergen et al, 2002;Osanai et al, 2005;Sendersky et al, 2005;Lahmi et al, 2006;Salinas et al, 2007;Zabulon et al, 2007;Kato et al, 2008Kato et al, , 2011Ruiz et al, 2008;Leganes et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

The proteolysis adaptor, NblA, initiates protein pigment degradation by interacting with the cyanobacterial light‐harvesting complexes

et al. 2014

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SUMMARYDegradation of the cyanobacterial protein pigment complexes, the phycobilisomes, is a central acclimation response that controls light energy capture. The small protein, NblA, is essential for proteolysis of these large complexes, which may reach a molecular mass of up to 4 MDa. Interactions of NblA in vitro supported the suggestion that NblA is a proteolysis adaptor that labels the pigment proteins for degradation. The mode of operation of NblA in situ, however, remained unresolved. Particularly, it was unclear whether NblA interacts with phycobilisome proteins while part of the large complex, or alternatively interaction with NblA, necessitates dissociation of pigment subunits from the assembly. Fluorescence intensity profiles demonstrated the preferential presence of NblA::GFP (green fluorescent protein) at the photosynthetic membranes, indicating co-localization with phycobilisomes. Furthermore, fluorescence lifetime imaging microscopy provided in situ evidence for interaction of NblA with phycobilisome protein pigments. Additionally, we demonstrated the role of NblA in vivo as a proteolysis tag based on the rapid degradation of the fusion protein NblA::GFP compared with free GFP. Taken together, these observations demonstrated in vivo the role of NblA as a proteolysis adaptor. Additionally, the interaction of NblA with phycobilisomes indicates that the dissociation of protein pigment subunits from the large complex is not a prerequisite for interaction with this adaptor and, furthermore, implicates NblA in the disassembly of the protein pigment complex. Thus, we suggest that, in the case of proteolysis of the phycobilisome, the adaptor serves a dual function: undermining the complex stability and designating the dissociated pigments for degradation.

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Section: Introductionmentioning

confidence: 99%

The proteolysis adaptor, NblA, initiates protein pigment degradation by interacting with the cyanobacterial light‐harvesting complexes

et al. 2014

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“…6A) exists with the homologue in cyanophage Ma-LMM01, which belongs to the Myoviridae (64). In cyanobacteria, NblA has been demonstrated to be a key protein of thylakoid and phycobilisome degradation and to result in a color change of cyanophage cultures from normal blue-green to chlorotic yellow (2,7,9). To reveal the function of PaV-LD NblA, we expressed the NblA fusion protein and prepared the anti-NblA antibody.…”

Section: Feature Ofmentioning

confidence: 99%

A Novel Cyanophage with a Cyanobacterial Nonbleaching Protein A Gene in the Genome

Gao

Gui

Zhang

2012

J Virol

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A cyanophage, PaV-LD, has been isolated from harmful filamentous cyanobacterium Planktothrix agardhii in Lake Donghu, a shallow freshwater lake in China. Here, we present the cyanophage's genomic organization and major structural proteins. The genome is a 95,299-bp-long, linear double-stranded DNA and contains 142 potential genes. BLAST searches revealed 29 proteins of known function in cyanophages, cyanobacteria, or bacteria. Thirteen major structural proteins ranging in size from 27 kDa to 172 kDa were identified by SDS-PAGE and mass-spectrometric analysis. The genome lacks major genes that are necessary to the tail structure, and the tailless PaV-LD has been confirmed by an electron microscopy comparison with other tail cyanophages and phages. Phylogenetic analysis of the major capsid proteins also reveals an independent branch of PaV-LD that is quite different from other known tail cyanophages and phages. Moreover, the unique genome carries a nonbleaching protein A (NblA) gene (open reading frame [ORF] 022L), which is present in all phycobilisome-containing organisms and mediates phycobilisome degradation. Western blot detection confirmed that 022L was expressed after PaV-LD infection in the host filamentous cyanobacterium. In addition, its appearance was companied by a significant decline of phycocyanobilin content and a color change of the cyanobacterial cells from blue-green to yellow-green. The biological function of PaV-LD nblA was further confirmed by expression in a model cyanobacterium via an integration platform, by spectroscopic analysis and electron microscopy observation. The data indicate that PaV-LD is an exceptional cyanophage of filamentous cyanobacteria, and this novel cyanophage will also provide us with a new vision of the cyanophage-host interactions. Cyanophages are one kind of planktonic viruses that infect cyanobacteria (blue-green algae). Cyanophages and phages have amazing amounts of genetic diversity and biological activity in water environments (33,34,40,54). In either a freshwater or saltwater environment, cyanophages are ubiquitous and play an important role in water ecosystems (46,52,61,66). Generally, the complete genome sequences of cyanophages can provide significant clues for better understanding of the biological properties, ecological effects, and coevolutionary relationships between cyanophages and their hosts (10,17,18,21,27,29). Some cyanophage genomes have been sequenced (32,35,44,49,51,60,64), which has revealed the presence of cyanobacterial genes involved in central energy metabolism and their host's survival. For examples, some photosynthesis-related genes (psbA, hliP, and PSII) and stress-response genes (coding for chaperones and genes associated with bacterial motility and chemotaxis) have been described in cyanophages (4, 5, 31, 36, 47), most of which are transcribed together with essential cyanophage replication-related genes (6, 13, 30, 65). Moreover, a nonbleaching protein A (NblA) gene has been found from a lytic phage, Ma-LMM01, infecting Microcystis aerugi...

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“…It may be possible that the NblA protein of S. elongatus is rapidly degraded together with the PBS and, therefore, is not accumulated to a detectable level. Previous studies, however, indicated the presence of NblA from Tolypothrix PCC 7601 and Synechocystis PCC 6803 (16,42,43); thus, it may be suggested that NblA stability differs between various cyanobacterial strains (see "Discussion").…”

Section: The Cellular Level Of the Nbla Protein In S Elongatus Remaimentioning

confidence: 90%

“…Previous studies based on in vitro interaction of NblA with the PBS suggested that the protein interacts directly with rod components (16,42,43). The most detailed study was performed by Bienert et al (18) who identified interactions in vitro with PC and PEC and assigned critical roles for Leu-51 and Lys-53 (numbering according to the Anabaena chromosomal NblA sequence), located at the C terminus of the second helix.…”

Section: Discussionmentioning

confidence: 99%

“…PCC 6803, a cyanobacterium with two forms of NblA, low levels of protein were identified by immunoblotting (33). In the filamentous cyanobacterium Tolypothrix PCC 7601, NblA monomers could only be identified immunologically in cells grown in red light (42,43). In green light-grown cells, a protein of twice the molecular weight of the NblA was labeled by the polyclonal antibodies, and its molecular identity could only be suggested as an SDS resistant dimer.…”

Section: Discussionmentioning

confidence: 99%

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Structural, Functional, and Mutational Analysis of the NblA Protein Provides Insight into Possible Modes of Interaction with the Phycobilisome

Dines

Sendersky

David

et al. 2008

Journal of Biological Chemistry

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The enormous macromolecular phycobilisome antenna complex (>4 MDa) in cyanobacteria and red algae undergoes controlled degradation during certain forms of nutrient starvation. The NblA protein (ϳ6 kDa) has been identified as an essential component in this process. We have used structural, biochemical, and genetic methods to obtain molecular details on the mode of action of the NblA protein. We have determined the three-dimensional structure of the NblA protein from both the thermophilic cyanobacterium Thermosynechococcus vulcanus and the mesophilic cyanobacterium Synechococcus elongatus sp. PCC 7942. The NblA monomer has a helix-loop-helix motif which dimerizes into an open, four-helical bundle, identical to the previously determined NblA structure from Anabaena. Previous studies indicated that mutations to NblA residues near the C terminus impaired its binding to phycobilisome proteins in vitro, whereas the only mutation known to affect NblA function in vivo is located near the protein N terminus. We performed random mutagenesis of the S. elongatus nblA gene which enabled the identification of four additional amino acids crucial for NblA function in vivo. This data shows that essential amino acids are not confined to the protein termini. We also show that expression of the Anabaena nblA gene complements phycobilisome degradation in an S. elongatus NblA-null mutant despite the low homology between NblAs of these cyanobacteria. We propose that the NblA interacts with the phycobilisome via "structural mimicry" due to similarity in structural motifs found in all phycobiliproteins. This suggestion leads to a new model for the mode of NblA action which involves the entire NblA protein.

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Immunolocalization of NblA, a protein involved in phycobilisome turnover, during heterocyst differentiation in cyanobacteria

Cited by 11 publications

References 28 publications

The proteolysis adaptor, NblA, initiates protein pigment degradation by interacting with the cyanobacterial light‐harvesting complexes

The proteolysis adaptor, NblA, initiates protein pigment degradation by interacting with the cyanobacterial light‐harvesting complexes

A Novel Cyanophage with a Cyanobacterial Nonbleaching Protein A Gene in the Genome

Structural, Functional, and Mutational Analysis of the NblA Protein Provides Insight into Possible Modes of Interaction with the Phycobilisome

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