8/25/03 (VJC)
Recommended reading from recent literature (2003)

1. Auxin action in a cell-free system.
Dharmasiri N, Dharmasiri S, Jones AM, Estelle M
Curr Biol 2003 Aug 19 13(16):1418-22 [abstract on PubMed]
PMID: 12932326

This interesting study suggests that the whole auxin signal transduction pathway including perception could be present in a soluble fraction based on the auxin-stimulated TIR1 and Aux/IAA protein interaction assay in vitro. The authors also show that the auxin response is prevented by an inhibitor of peptidyl-prolyl isomerase, juglone, and does not require protein kinase and phosphatase activities. The new and simple assay will be valuable in the identification of auxin signaling components upstream of Aux/IAA proteins.

2. SIR1, an Upstream Component in Auxin Signaling Identified by Chemical Genetics.
Zhao Y, Dai X, Blackwell HE, Schreiber SL, Chory J
Science 2003 Aug 22 301(5636):1107-10 [abstract on PubMed]
PMID: 12893885

The authors use a chemical genetic approach to identify a novel auxin signaling gene SIR1 (SIrtinol Resistance 1), that encodes a hybrid protein of a ubiquitin-activating-enzyme E1-like domain and a Rhodanese-like domain that shares homology with the C-terminal domain of prolyl isomerase. It is suggested that SIR1 might be a negative regulator in auxin signaling, and might interact with prolyl isomerase and influence the conformation of two essential proline residues important for Aux/IAA protein degradation induced by auxin. It will be interesting to determine the precise role of SIR1 and sir1 in auxin signaling.

3. Inducers of plant systemic acquired resistance regulate NPR1 function through redox changes.
Mou Z, Fan W, Dong X
Cell 2003 Jun 27 113(7):935-44 [abstract on PubMed]
PMID: 12837250
This exciting paper shows that NPR1 is switching from cytoplasmic oligomers to nuclear monomers to activate PR1 expression in response to salicylic acid and intracellular redox potential. Mutations of NPR1 (C82A and C216A) confer constitutive monomer state, nuclear localization and PR1 activation. The studies have turned SA-dependent oxidative signaling to anti-oxidative signaling which might explain the relatively slow and indirect nature of full-induction of PR gene expression by salicylic acid.

4. Salicylic Acid and NPR1 Induce the Recruitment of trans-Activating TGA Factors to a Defense Gene Promoter in Arabidopsis.
Johnson C, Boden E, Arias J
Plant Cell 2003 Aug 15(8): 1846-58 [abstract on PubMed]
PMID: 12897257

This interesting paper shows that the direct binding of TGA2 and TGA3 transcription factors to the promoter of their target gene PR1 is induced by salicylic acid in a NPR1 dependent manner. The conclusion is made based on comprehensive results from in vitro DNA binding analysis with WT and npr1 nuclear extracts, TGA antibody depletion, endogenous gene activation, ChIP analysis of in vivo DNA binding by TGA2 and TGA3, and transfection assays. The studies demonstrate the power of using an integrated approach by combining in vitro and in vivo molecular analyses with genetics to unravel the molecular mechanism underlying a key salicylic acid response.

5. A nucleosomal function for IkappaB kinase-alpha in NF-kappaB-dependent gene expression.
Anest V, Hanson JL, ..., Strahl BD, Baldwin AS
Nature 2003 Jun 5 423(6940):659-63 [abstract on PubMed]
PMID: 12789343

6. A B cell-based sensor for rapid identification of pathogens.
Rider TH, Petrovick MS, ..., Chen J, Hollis MA
Science 2003 Jul 11 301(5630):213-5 [abstract on PubMed]
PMID: 12855808

7. BAD and glucokinase reside in a mitochondrial complex that integrates glycolysis and apoptosis.
Danial NN, Gramm CF, ..., Gygi SP, Korsmeyer SJ
Nature 2003 Aug 21 424(6951):952-6 [abstract on PubMed]
PMID: 12931191
8. S phase activation of the histone H2B promoter by OCA-S, a coactivator complex that contains GAPDH as a key component.
Zheng L, Roeder RG, Luo Y
Cell 2003 Jul 25 114(2):255-66 [abstract on PubMed]
PMID: 12887926

9. Identification of Hedgehog pathway components by RNAi in Drosophila cultured cells.
Lum L, Yao S, ..., Nirenberg M, Beachy PA
Science 2003 Mar 28 299(5615):2039-45 [abstract on PubMed]
PMID: 12663920