ISSN 10214437, Russian Journal of Plant Physiology, 2011, Vol. 58, No. 1, pp. 149–156. © Pleiades Publishing, Ltd., 2011.
Physiological, genetic, and biochemical studies
have implicated the role of plant hormone auxin in the
regulation of diverse developmental and physiological
processes, including apical dominance, photo and
gravitropism, embryogenesis, vascular differentiation,
organogenesis, and root and shoot architecture [1–3].
There is also evidence suggesting that this hormone
may regulate anther dehiscence, pollen development,
and filament elongation in tobacco [4, 5]. Auxin coor
dinates many plant growth and developmental pro
cesses by modulating gene expression, which leads to
changes in cell division, elongation, and differentia
tion [3, 6–8]. How the auxin signal is perceived and
interpreted by plant cells has been a central question in
Most plant cells have the ability to interpret auxin
signals through a short nuclear signaling pathway. The
crucial, but for long unresolved, question in auxin sig
This text was submitted by the authors in English.
These authors contributed equally to this work.
naling concerned the mechanism of auxin perception
and the identity of the auxin receptor. In
, a Skp1cullinF box protein (SCF) E3 ubiq
uitin ligase, such as the Fbox component called
TRANSPORT INHIBITOR RESPONSE 1 (TIR1),
could bind auxin at physiologically relevant concen
trations. Furthermore, auxin could enhance the inter
action between TIR1 and Auxin/IAA (Aux/IAA) [9,
10]. Crystallographic analysis of this interaction shows
that TIR1 contains a hydrophobic pocket, in which
auxin and various auxin analogs can bind. Interest
ingly, auxin does not change the conformation of
TIR1 but instead acts as a “molecular glue” by filling
a hydrophobic cavity at the interaction interface,
thereby enhancing TIR1–Aux/IAA interactions .
These observations demonstrate that individual cells
interpret auxin largely by a nuclear signaling pathway
that involves the Fbox protein TIR1 acting as an
auxin receptor, and the auxindependent TIR1 activ
ity leads to ubiquitinationbased degradation of tran
scriptional repressors and complex transcriptional
Until now, there is hardly any information about
genes encoding TIR1 in plants except for
In the present study, by using the rapid amplification
of cDNA ends (RACE) method, we isolated a novel
Molecular Cloning and Characterization of a
INHIBITOR RESPONSE 1
a, b, c
, Caohao Zhang
, Hui Yang
, Xiangyang Lu
, Peiwang Li
, and Xianguo Qing
College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha 410128, China;
Hunan Agricultural Bioengineering Research Institute, Changsha 410128, China
Yuan Long Ping HighTech Agriculture CO., LTD, Changsha 410001, China
Hunan Forestry Academy, Changsha 410004, China
Received September 26, 2009
—The fulllength cDNA encoding a TRANSPORT INHIBITOR RESPONSE 1 (TIR1) protein,
, was isolated for the first time from
by the rapid amplification of cDNA
ends (RACE) method.
contained a 1746bp open reading frame encoding 581 amino acids. The
deduced NtTIR1 protein, which showed high identity to TIR1 protein of other dicotyledonous plants, had a
calculated mol wt of 65.2 kD and a theoretical pI value of 6.02 and was predicted to possess an Fbox domain.
Bioinformatic analyses revealed that the deduced NtTIR1 contained three transmembrane domains, and the
predicted 3D model of NtTIR1 had a typical spatial structure of the TIR1 protein from
Transcription pattern analysis revealed that the transcription of
was induced by IAA and ABA. Clon
ing of the
gene will enable us to further understand the molecular organization of the TIR1 and its
possible function in the tobacco.
Keywords: Nicotiana tabacum
, TIR1, RACE.
Aux—auxin; Et—ethylene; MeJa—methyl jas
monic acid; ORF—open reading frame; RACE—rapid amplifi
cation of cDNA ends; SCF—Skp1cullinF box protein;
TIR1—transport inhibitor response 1 protein.