AtHIPM, an ortholog of the apple HrpN-interacting protein, is a negative regulator of plant growth and mediates the growth-enhancing effect of HrpN in Arabidopsis.
HrpN (harpin) protein is critical to the virulence of the fire blight pathogen Erwinia amylovora in host plants like apple (Malus x domestica). Moreover, exogenous treatment of Arabidopsis (Arabidopsis thaliana), a nonhost plant, with partially purified HrpN enhances growth. To address the bases of the effects of HrpN in disease, we sought a HrpN-interacting protein(s) in apple, using a yeast two-hybrid assay. A single positive clone, designated HIPM (HrpN-interacting protein from Malus), was found. HIPM, a 6.5-kD protein, interacted with HrpN in yeast and in vitro. Deletion analysis showed that the N-terminal 198 of 403 amino acids of HrpN are required for interaction with HIPM. HIPM orthologs were found in Arabidopsis (AtHIPM) and rice (Oryza sativa; OsHIPM). HrpN also interacted with AtHIPM in yeast and in vitro. In silico analyses revealed that the three plant proteins contain putative signal peptides and putative transmembrane domains. We showed that both HIPM and AtHIPM have functional signal peptides, and green fluorescent protein-tagged HIPM and AtHIPM associated, in clusters, with plasma membranes. Both HIPM and AtHIPM are expressed constitutively; however, they are expressed more strongly in apple and Arabidopsis flowers than in leaves and stems. The size of AtHIPM knockout mutant plants of Arabidopsis was slightly larger than the wild-type plants. Interestingly, the knockout mutant did not exhibit enhanced plant growth in response to treatment with HrpN. Overexpression of AtHIPM conversely resulted in smaller plants. These results indicate that AtHIPM functions as a negative regulator of plant growth and mediates enhanced growth that results from treatment with HrpN.
Oh
Chang-Sik
CS
Department of Plant Pathology, Cornell University, Ithaca, New York 14853, USA.
Beer
Steven V
SV
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001425:Bacterial Outer Membrane Proteins / Q000378:metabolism* / Q000494:pharmacology; D027845:Malus; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D011485:Protein Binding
D029681:Arabidopsis Proteins; D001425:Bacterial Outer Membrane Proteins; C525276:HrpN-interacting protein, Arabidopsis; D008565:Membrane Proteins; C075462:harpin protein, Erwinia amylovora
Development. 1997 Aug;124(16):3177-84
9272958
Cell. 1993 Jul 2;73(7):1255-66
8324821
Plant Physiol. 2004 Nov;136(3):3628-38
15516507
Plant Physiol. 1967 Mar;42(3):415-20
16656519
Planta. 2005 Dec;223(1):5-19
16136329
Annu Rev Phytopathol. 2004;42:385-414
15283671
J Exp Bot. 2005 Aug;56(418):2229-38
15983008
Plant J. 1998 Dec;16(6):735-43
10069079
Plant Cell. 1990 Jun;2(6):513-23
2152173
Cell Microbiol. 1999 Sep;1(2):131-41
11207547
J Bacteriol. 2004 Sep;186(18):6239-47
15342594
Curr Biol. 2000 Nov 16;10(22):R823-5
11102822
Proc Natl Acad Sci U S A. 2001 Jan 2;98(1):289-94
11134504
Mol Plant Pathol. 2005 Mar 1;6(2):125-38
20565644
Proc Natl Acad Sci U S A. 1992 Aug 1;89(15):6837-40
11607311
J Bacteriol. 1998 Oct;180(19):5211-7
9748456
Plant Mol Biol. 1998 Mar;36(4):521-8
9484447
J Bacteriol. 2002 Mar;184(5):1340-8
11844763
J Bacteriol. 1998 Oct;180(19):5203-10
9748455
Plant Mol Biol. 1999 Aug;40(6):945-57
10527419
Mol Microbiol. 2005 Dec;58(5):1406-20
16313625
FEBS Lett. 2001 May 25;497(2-3):82-4
11377417
EMBO J. 1994 Feb 1;13(3):543-53
8313899
Mol Plant Microbe Interact. 1995 Jul-Aug;8(4):484-91
8589405
Mol Plant Microbe Interact. 2006 Jan;19(1):53-61
16404953
EMBO J. 2003 Jan 2;22(1):60-9
12505984
J Biol Chem. 2007 May 4;282(18):13601-9
17314101
Plant J. 1999 Oct;20(2):207-15
10571880
Science. 1992 Jul 3;257(5066):85-8
1621099
J Bacteriol. 2003 May;185(10):3155-66
12730176