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Stéphane HACQUARD (INRA NANCY) The secretome of Melampsora larici-populina First results Nancy, workshop Melampsora, august 2008 David JOLY (CFL QUEBEC)
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I- Introduction Hahn and Mendgen 1997: haustorial ESTs from U. fabae Early stages of host infection marked by the activation of many genes: PIGs (in Planta Induced Genes) Transport: genes encoding transporters: PIG2- HXT1 (Hahn et al, 1997; Voegele et al, 2001) Biosynthesis: genes involved in thiamine biosynthesis (THI1; THI4) (Sohn et al, 2000) Trafficking an signalling process : RTP1 (Kemen et al, 2005) Small secreted proteins ( SSP ) and the establishment of fungal biotrophy M. larici-populina: obligate biotrophic fungus completely dependant on living plant tissues for growth and development Specialized infection structure: haustorium
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I- Introduction Catanzariti et al, 2006: haustorial ESTs from M. lini Focus on the secreted proteins Identification of 21 transcripts encoding Haustorially Expressed Secreted Protein (HESPs) Among HESPs: AvrL567, expressed in haustoria and trigger specific hypersensitive response-like necrosis that is dependant on the co- expression of the L5, L6, L7 resistance genes (Dodds et al, 2004; Dodds et al, 2006) AvrL567 L9 L5 L6 L7
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I- Introduction Kämper et al., 2006: Ustilago maydis secreted proteins 18.6% SP organized in 12 clusters Unaffected (7) Non pathogenic (1) Reduced (3) Clustering of genes encoding secreted proteinsVirulence of deletion mutants increased (1) SP could trigger defense responses in the host plant (Avr genes) or manipulate host cell structure and fonction to facilitate infection Deletion of individual clusters altered the virulence of U. maydis in five cases, ranging from a complete lack of symptoms to hypervirulence
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What we need to know ? Protein length Amino acid composition of proteins Subcellular localization Presence / Absence of a signal peptide Protein topology: transmembrane domains Softwares used PEPSTATS TargetP SignalP TMHMM A combination of different prediction softwares II- The secretome pipeline:
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Why a pipeline ? Limitation of online prediction program: - number of proteins - length of sequences - number of jobs Local program: - faster than online services - can apply routine filter to the result 1 command for all computational methods II- The secretome pipeline:
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Sequence filter Gene models Prediction of a signal peptide by TargetP At least two positive scores by SignalP (Nancy) No transmembrane domains but one domain allowed: N-terminal domain overlaping signal peptide Gene models 300 amino acids SUBCELLULAR LOCALIZATION TOPOLOGY LENGTH II- The secretome pipeline: 2 positive NN scores (Smax and D) plus HMM score by SignalP (Quebec)
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III- The secretome of Melampsora larici-populina Gene models Prediction of a signal peptide by targetP At least two positive prediction methods of a signal peptide by signalP No transmembrane domains but one domain allowed: N-terminal domain overlaping signal peptide Gene models 300 amino acids Nancy 16694 2633 (15,8%) 2125 (12,7%) 1848 (11%) 961 (5,7%) GhentQuebec 797 (4,8%)818 (4,9%) 1-SSP prediction 16694
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SSP predicted by the 3 pipelines - Nancy, Ghent, Quebec: 720 SSP predicted by 2 pipelines - Nancy, Quebec: 91 - Nancy, Ghent: 52 - Quebec, Ghent: 6 SSP predicted by only one pipeline - Nancy: 98 - Ghent: 15 - Quebec: 3 III- The secretome of Melampsora larici-populina 1- SSP prediction : 985 putative SSP in Melampsora genome MelampsoraPucciniaLaccaria Gene models166942056720613 SSP 300aa 985 (5,8%)1219 (5,9%)864 (4,2%) 149 116
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III- The secretome of Melampsora larici-populina Among the 985 predicted SSP: 171 hits: hypothetical protein 76 show homology with: 234 contain more than 8 cysteines 320 show homology with Puccinia 2- Putative SSP homology Kemen et al. (2005) MPMI 18: 1130-1139 - Avirulence genes (AvrL567; AvrM) and Haustorially expressed secreted protein (HESP178, 327, 376, 379, 417, 570, 767, 897, c55, C63, c66, c49) from Melampsora lini. (Dodds et al., 2004; Catanzariti et al., 2006) - Rust transferred protein (RTP1) from Uromyces fabae (Kemen et al., 2005) - Thaumatin, GPI anchored CFEM domain protein, expansin, laccase … %C: all genes: 1,38 / SSP: 2,64 only 247 show homology with nr
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III- The secretome of Melampsora larici-populina 3- SSP families TRIBE-MCL: provides gene family identification based on all-vs-all sequence similarity results. 233 SSP belong to 97 families only composed of secreted proteins (largest:14 members, smallest: 2 members). 151 SSP belong to families composed of both secreted and non secreted proteins 601 SSP correspond to single gene model - large majority of uncharacterized families - Curation of mispredicted SSPs (NS => S or S => NS)
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III- The secretome of Melampsora larici-populina 4- SSP annotation August 2008: 401 SSP manually curated (S + D) 114 new or modified gene models (29%) 287 gene models were correctly predicted (71%) EuGene: 103 gene models predicted (35%) fgenesh1: 110 gene models predicted (38%) fgenesh2: 201 gene models predicted (70%) 18 NS => S Among 155 SSP manually curated corresponding to single model: 45 show homology with others gene models (blastp) or genomic regions (tblastn) => New families
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III- The secretome of Melampsora larici-populina 4- SSP annotation Missed models… One superfamily with more than 30 members Conserved structure and cysteine residues Around half were missed by gene predictors
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III- The secretome of Melampsora larici-populina 5- SSP clusters Secreted Non secreted Scaffold 31: Scaffold 11: Cutinase Homology with RTP1 1kb Homology with HESP-417 Hypothetical protein 27 clusters of at least 3 SSP separeted by no more than 3 non secreted proteins.
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6- SSP expression data III- The secretome of Melampsora larici-populina Melampsora cDNA libraries Urediniospores library (Sanger ESTs) : - M. larici-populina spores and germlings (JGI, Nancy) 52,269 ESTs Infected poplar leaves library (454 pyrosequencing ESTs) : - M. larici-populina 98AG31 infected ‘Beaupré’ leaves (compatible interaction) at 4 dpi and 7 dpi (50/50mixed) 4679 ESTs Melampsora 5533 ESTs poplar
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6- SSP expression data III- The secretome of Melampsora larici-populina 985 SSP: 323 supported by EST (33%) 58 only supported by spores ESTs (sanger) 97 supported by both spores and infected leaves ESTs (Sanger and 454) 168 only supported by infected leaves ESTs (454) 58 SSP only supported by spores ESTs 19 homologies with nr, 5 hits against known proteins
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III- The secretome of Melampsora larici-populina 97 SSP supported by both spores and infected leaves ESTs 6- SSP expression data - Most ESTs belong to spores: 51 homologies with nr, 17 hits against known proteins - Most ESTs belong to infected leaves:
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III- The secretome of Melampsora larici-populina 6- SSP expression data 168 SSP only supported by infected leaves ESTs 47 homologies with nr, 15 hits against known proteins
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III- The secretome of Melampsora larici-populina 6- SSP expression data 0 20 40 60 80 100 120 Sp2612244896168 0 20 40 60 80 100 120 140 160 180 Sp2 6 12 24 4896 168 0 20 40 60 80 100 120 140 Sp2612244896 168 0 20 40 60 80 100 120 140 160 Sp2612244896168 0 20 40 60 80 100 120 140 Sp2612244896 168 0 20 40 60 80 100 120 140 160 Sp2612244896168 Relative expression of M. larici- populina genes (2- ∆Ct ) to ElF and Tub reference genes by RT-qPCR. Time (hours post-inoculation) Effectors previously described in Pucciniales are also expressed in M. larici-populina. Specific transcripts profiles are observed at the different stages of the infectious process. Interestingly, two genes encoding RTP1 homologues have distinct expression profiles.
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III- The secretome of Melampsora larici-populina 7- SSP evolutionary constraints HGGLocBLASTX against Fungi nrE-valueCysω 205NSNo hitND2.68 254NSNo hitND2.59 1278NS ref|XP_001211022.1| conserved hypothetical protein [Aspergillus terreus] 3e-07ND1.88 28SNo hit01.38 92S gb|AAS45284.1| proline-rich antigen [Chrysosporium lucknowense] 4e-0961.43 729S gb|EAT81533.2| hypothetical protein [Phaeosphaeria nodorum] 7e-1181.32 747S ref|XP_757360.1| hypothetical protein [Ustilago maydis] 1e-0441.95 4191SNo hit41.57 5606SNo hit61.76 5610SNo hit64.31 5617SNo hit01.23 5624SNo hit81.93 6067S ref|XP_758577.1| hypothetical protein [Ustilago maydis] 6e-06101.27 Positive selection screen on an EST data set… Application to whole genome?
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V- Conclusions 985 putative SSP in Melampsora genome (5.8%) Homology with effectors previously described in Pucciniale 33% supported by ESTs 660 SSP specific of Melampsora Most of SSP expressed during infection process Validation data: Biological approch - NimbleGen micro-array - RT-qPCR - immunolocalization
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Acknowledgment NANCY: Emilie TISSERANT Benoit HILSELBERGER Marie Pierre OUDOT-LE SECQ Sébastien DUPLESSIS Francis MARTIN GHENT: Yao-Cheng LIN Yves van De Peer JGI sequencing and annotation teamQUEBEC: Nicolas FEAU Richard HAMELIN
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