scholarly journals Functional Analyses of the Pto Resistance Gene Family in Tomato and the Identification of a Minor Resistance Determinant in a Susceptible Haplotype

2002 ◽  
Vol 15 (3) ◽  
pp. 281-291 ◽  
Author(s):  
Jeff H. Chang ◽  
Yin-Shan Tai ◽  
Adriana J. Bernal ◽  
Daniel T. Lavelle ◽  
Brian J. Staskawicz ◽  
...  

Pto is a member of a multigene family and encodes a serine/threonine kinase that mediates gene-for-gene resistance to strains of Pseudomonas syringae pv. tomato expressing avrPto. The inferred amino acid sequence of the Pto homologs from both resistant (LpimPth2 to LpimPth4,) and susceptible (LescFen, LescPth2 to LescPth5) haplotypes suggested that most could encode functional serine/threonine kinases. In addition, the activation segments of the homologs are similar in sequence to that of Pto, and some have residues previously identified as required for binding of AvrPto by Pto in the yeast two-hybrid system. The Pto homologs were therefore characterized for transcription, for the ability of their products to interact with AvrPto in the yeast two-hybrid system, for their autophos-phorylation activity, and for their potential to elicit cell death in the presence of and absence of a ligand, as well as their dependence on Prf. LpimPth5, LpimPth4, and LescPth4 were not transcribed at levels detectable by reverse transcription-polymerase chain reaction. The interaction with AvrPto was unique to Pto in the yeast two-hybrid system. LescPth2 autophosphorylated in vitro as a fusion protein. LpimPth2, LpimPth3, LpimPth4, LescPth3, and LescPth4 did not autophosphorylate in vitro. Transient expression of wild-type Fen and wild-type LpimPth3, as well as LescFen, LescPth3, and LescPth5 with perturbations in their P+1 loop caused cell death in Nicotiana benthamiana. LpimPth3 and LescPth3 with amino acid substitutions in the P+1 loop also elicited cell death in tomato; this was dependent on the presence of wild-type Prf. Consequently, some homologs could potentially encode functional resistance proteins. LescPth5 induced cell death specifically in response to expression of AvrPto in tobacco in a Prf-dependent manner; this is consistent with a homolog from a ‘susceptible’ haplotype encoding a minor recognition determinant.

2001 ◽  
Vol 276 (15) ◽  
pp. 11980-11987 ◽  
Author(s):  
Steven A. Haney ◽  
Elizabeth Glasfeld ◽  
Cynthia Hale ◽  
David Keeney ◽  
Zhizhen He ◽  
...  

The recruitment of ZipA to the septum by FtsZ is an early, essential step in cell division inEscherichia coli. We have used polymerase chain reaction-mediated random mutagenesis in the yeast two-hybrid system to analyze this interaction and have identified residues within a highly conserved sequence at the C terminus of FtsZ as the ZipA binding site. A search for suppressors of a mutation that causes a loss of interaction (ftsZD373G) identified eight different changes at two residues within this sequence.In vitro, wild type FtsZ interacted with ZipA with a high affinity in an enzyme-linked immunosorbent assay, whereas FtsZD373Gfailed to interact. Two mutant proteins examined restored this interaction significantly.In vivo, the alleles tested are significantly more toxic than the wild typeftsZand cannot complement a deletion. We have shown that a fusion, which encodes the last 70 residues of FtsZ in the two-hybrid system, is sufficient for the interaction with FtsA and ZipA. However, when the wild type sequence is compared with one that encodes FtsZD373G, no interaction was seen with either protein. Mutations surrounding Asp-373 differentially affected the interactions of FtsZ with ZipA and FtsA, indicating that these proteins bind the C terminus of FtsZ differently.


Genetics ◽  
1996 ◽  
Vol 144 (3) ◽  
pp. 1087-1095 ◽  
Author(s):  
Allan R Lohe ◽  
David T Sullivan ◽  
Daniel L Hartl

Abstract We have studied the Mos1 transposase encoded by the transposable element mariner. This transposase is a member of the “D,D(35)E” superfamily of proteins exhibiting the motif D,D(34)D. It is not known whether this transposase, or other eukaryote transposases manifesting the D,D(35)E domain, functions in a multimeric form. Evidence for oligomerization was found in the negative complementation of Mos1 by an EMS-induced transposase mutation in the catalytic domain. The transposase produced by this mutation has a glycine-to-arginine replacement at position 292. The G292R mutation strongly interferes with the ability of wild-type transposase to catalyze excision of a target element. Negative complementation was also observed for two other EMS mutations, although the effect was weaker than observed with G292R. Results from the yeast two-hybrid system also imply that Mos1 subunits interact, suggesting the possibility of subunit oligomerization in the transposition reaction. Overproduction of Mos1 subunits through an hsp70 promoter also inhibits excision of the target element, possibly through autoregulatory feedback on transcription or through formation of inactive or less active oligomers. The effects of both negative complementation and overproduction may contribute to the regulation of mariner transposition.


1994 ◽  
Vol 14 (11) ◽  
pp. 7483-7491
Author(s):  
A Kikuchi ◽  
S D Demo ◽  
Z H Ye ◽  
Y W Chen ◽  
L T Williams

Using a yeast two-hybrid system, we identified a novel protein which interacts with ras p21. This protein shares 69% amino acid homology with ral guanine nucleotide dissociation stimulator (ralGDS), a GDP/GTP exchange protein for ral p24. We designated this protein RGL, for ralGDS-like. Using the yeast two-hybrid system, we found that an effector loop mutant of ras p21 was defective in interacting with the ras p21-interacting domain of RGL, suggesting that this domain binds to ras p21 through the effector loop of ras p21. Since ralGDS contained a region highly homologous with the ras p21-interacting domain of RGL, we examined whether ralGDS could interact with ras p21. In the yeast two-hybrid system, ralGDS failed to interact with an effector loop mutant of ras p21. In insect cells, ralGDS made a complex with v-ras p21 but not with a dominant negative mutant of ras p21. ralGDS interacted with the GTP-bound form of ras p21 but not with the GDP-bound form in vitro. ralGDS inhibited both the GTPase-activating activity of the neurofibromatosis gene product (NF1) for ras p21 and the interaction of Raf with ras p21 in vitro. These results demonstrate that ralGDS specifically interacts with the active form of ras p21 and that ralGDS can compete with NF1 and Raf for binding to the effector loop of ras p21. Therefore, ralGDS family members may be effector proteins of ras p21 or may inhibit interactions between ras p21 and its effectors.


1996 ◽  
Vol 16 (4) ◽  
pp. 1576-1583 ◽  
Author(s):  
B E Strober ◽  
J L Dunaief ◽  
Guha ◽  
S P Goff

hBRG1 and hBRM are mammalian homologs of the SNF2/SW12 yeast transcriptional activator. These proteins exist in a large multisubunit complex that likely serves to remodel chromatin and, in so doing, facilitates the function of specific transcription factors. The retinoblastoma protein (pRB) inhibits cell cycle progression by repressing transcription of specific growth-related genes. Using the yeast two-hybrid system, we demonstrate that the members of the hBRG1/hBRM family of proteins interact with the pRB family of proteins, which includes pRB, p107, and p130. Interaction between the hBRG1/hBRM family with the pRB family likely influences cellular proliferation, as both hBRG1 and hBRM, but not mutants of these proteins unable to bind to pRB family members, inhibit the formation of drug-resistant colonies when transfected into the SW13 human adenocarcinoma cell line, which lacks endogenous hBRG1 or hBRM. Further, hBRM and two isoforms of hBRG1 induce the formation of flat, growth-arrested cells in a pRB family-dependent manner when introduced into SW13 cells. This flat-cell inducing activity is severely reduced by cotransfection of the wild-type E1A protein and variably reduced by the cotransfection of mutants of E1A that lack the ability to bind to some or all members of the pRB family.


1995 ◽  
Vol 128 (3) ◽  
pp. 263-271 ◽  
Author(s):  
J Staudinger ◽  
J Zhou ◽  
R Burgess ◽  
S J Elledge ◽  
E N Olson

Protein kinase C (PKC) plays a central role in the control of proliferation and differentiation of a wide range of cell types by mediating the signal transduction response to hormones and growth factors. Upon activation by diacylglycerol, PKC translocates to different subcellular sites where it phosphorylates numerous proteins, most of which are unidentified. We used the yeast two-hybrid system to identify proteins that interact with activated PKC alpha. Using the catalytic region of PKC fused to the DNA binding domain of yeast GAL4 as "bait" to screen a mouse T cell cDNA library in which cDNA was fused to the GAL4 activation domain, we cloned several novel proteins that interact with C-kinase (PICKs). One of these proteins, designated PICK1, interacts specifically with the catalytic domain of PKC and is an efficient substrate for phosphorylation by PKC in vitro and in vivo. PICK1 is localized to the perinuclear region and is phosphorylated in response to PKC activation. PICK1 and other PICKs may play important roles in mediating the actions of PKC.


2003 ◽  
Vol 77 (1) ◽  
pp. 769-775 ◽  
Author(s):  
Pritsana Chomchan ◽  
Shi-Fang Li ◽  
Yukio Shirako

ABSTRACT We investigated the interaction of Rice grassy stunt tenuivirus (RGSV) nonstructural protein p5, a protein of 22 kDa encoded on vRNA 5, with all 12 RGSV proteins by using a GAL4 transcription activator-based yeast two-hybrid system. The p5 protein interacted only with itself and not with any other viral protein; the interacting domains were localized within the N-terminal 96 amino acids of p5. The p5-p5 interaction was reproduced in an Sos recruitment-mediated yeast two-hybrid system as well in by far-Western blots. Native p5 protein extracted from RGSV-infected rice tissue was detected in a large complex with a molecular mass of approximately 260 kDa composed of 12 molecules of p5 or a p5 oligomer with an unidentified host factor(s).


2003 ◽  
Vol 185 (8) ◽  
pp. 2393-2401 ◽  
Author(s):  
Yi-Ying Lee ◽  
Chiung-Fang Chang ◽  
Chueh-Ling Kuo ◽  
Meng-Ching Chen ◽  
Chien Hung Yu ◽  
...  

ABSTRACT The Escherichia coli ClpYQ (HslUV) is an ATP-dependent protease that consists of an ATPase large subunit with homology to other Clp family ATPases and a peptidase small subunit related to the proteasomal β-subunits of eukaryotes. Six identical subunits of both ClpY and ClpQ self-assemble into an oligomeric ring, and two rings of each subunit, two ClpQ rings surrounded by single ClpY rings, form a dumbbell shape complex. The ClpYQ protease degrades the cell division inhibitor, SulA, and a positive regulator of capsule transcription, RcsA, as well as RpoH, a heat shock sigma transcription factor. Using the yeast-two hybrid system, we explored the in vivo protein-protein interactions of the individual subunits of the ClpYQ protease involved in self-oligomerization, as well as in recognition of specific substrates. Interactions were detected with ClpQ/ClpQ, ClpQ/ClpY, and ClpY/SulA. No interactions were observed in experiments with ClpY/ClpY, ClpQ/RcsA, and ClpQ/SulA. However, ClpY, lacking domain I (ClpYΔI) was able to interact with itself and with intact ClpY. The C-terminal region of ClpY is important for interaction with other ClpY subunits. The previously defined PDZ-like domains at the C terminus of ClpY, including both D1 and D2, were determined to be indispensable for substrate binding. Various deletion and random point mutants of SulA were also made to verify significant interactions with ClpY. Thus, we demonstrated in vivo hetero- and homointeractions of ClpQ and ClpY molecules, as well as a direct association between ClpY and substrate SulA, thereby supporting previous in vitro biochemical findings.


2002 ◽  
Vol 13 (3) ◽  
pp. 1071-1082 ◽  
Author(s):  
Brian A. Rous ◽  
Barbara J. Reaves ◽  
Gudrun Ihrke ◽  
John A.G. Briggs ◽  
Sally R. Gray ◽  
...  

CD63 is a lysosomal membrane protein that belongs to the tetraspanin family. Its carboxyterminal cytoplasmic tail sequence contains the lysosomal targeting motif GYEVM. Strong, tyrosine-dependent interaction of the wild-type carboxyterminal tail of CD63 with the AP-3 adaptor subunit μ3 was observed using a yeast two-hybrid system. The strength of interaction of mutated tail sequences with μ3 correlated with the degree of lysosomal localization of similarly mutated human CD63 molecules in stably transfected normal rat kidney cells. Mutated CD63 containing the cytosolic tail sequence GYEVI, which interacted strongly with μ3 but not at all with μ2 in the yeast two-hybrid system, localized to lysosomes in transfected normal rat kidney and NIH-3T3 cells. In contrast, it localized to the cell surface in transfected cells ofpearl and mocha mice, which have genetic defects in genes encoding subunits of AP-3, but to lysosomes in functionally rescued mocha cells expressing the δ subunit of AP-3. Thus, AP-3 is absolutely required for the delivery of this mutated CD63 to lysosomes. Using this AP-3–dependent mutant of CD63, we have shown that AP-3 functions in membrane traffic from thetrans-Golgi network to lysosomes via an intracellular route that appears to bypass early endosomes.


Parasitology ◽  
2019 ◽  
Vol 147 (8) ◽  
pp. 865-872 ◽  
Author(s):  
Oliver Weth ◽  
Simone Haeberlein ◽  
Martin Haimann ◽  
Yinjie Zhang ◽  
Christoph G. Grevelding

AbstractSchistosomiasis is an acute and chronic disease caused by parasitic worms of the genus Schistosoma. Treatment is solely dependent on praziquantel. In the face of the worldwide dimension, projects have been initiated to develop new chemotherapies. Due to their proven druggability, G protein-coupled receptors (GPCRs) are promising targets for anthelmintics. However, to identify candidate receptors, a deeper understanding of GPCR signalling in schistosome biology is essential. Comparative transcriptomics of paired and unpaired worms and their gonads revealed 59 differentially regulated GPCR-coding genes putatively involved in neuronal processes. In general, the diversity among GPCRs and their integral membrane topology make it difficult to characterize and deorphanize these receptors. To overcome existing limitations, we performed a pilot approach and utilized the innovative Membrane-Anchored Ligand And Receptor yeast two-hybrid system (MALAR-Y2H) to associate potential neuropeptide ligands with their cognate receptors. Here, we demonstrated the ability to express full-length GPCRs of Schistosoma mansoni in a heterologous yeast-based system. Additionally, we localized GPCRs and chimeras of neuropeptides fused to the WBP1 transmembrane domain of yeast to the plasma membrane of yeast cells. Reporter gene assays indicated ligand-receptor binding, which allowed us to identify certain neuropeptides as potential ligands for two GPCRs, which had been found before to be differentially expressed in schistosomes in a pairing-dependent manner. Thus, the MALAR-Y2H system appears suitable to unravel schistosome GPCR–ligand interactions. Besides its relevance for understanding schistosome biology, identifying and characterizing GPCR–ligand interaction will also contribute to applied research aspects.


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