A novel protein with DNA binding activity from tobacco chloroplast nucleoids.

Abstract

A 41 -kD DNA binding protein with a basic pl was purified from chloroplast nucleoids in photomixotrophically cultured tobacco cells, and its amino acid sequence was determined. Using this sequence information, its cDNA (CND41) was isolated, and its nucleotide sequence was determined. The predicted amino acid sequence of CND41 has a transit peptide of 120 amino acids and a mature protein of 382 amino acids. A distinctive helix-turn-helix motif in the lysine-rich N-terminal region of the mature protein and an aspartyl protease active site motif were predicted. Expression of a series of truncated CND41 proteins in Escherichia coli indicated that the lysine-rich region is essential for DNA binding and that CND41 nonspecifically binds chloroplast DNA. Protein gel blot analyses showed CND41 mainly in cells and/or tissues containing nonphotosynthesizing, actively growing plastids. In addition, the accumulation of chloroplast transcripts in these cells and/or tissues (e.g., transcripts for Qe binding protein of photosystem II [@A] and large subunit of ribulose bisphosphate carboxylase [rbcL]) was negatively correlated with the accumulation of CND41. Analyses of cultured cells of transgenic tobacco with reduced CND41 levels showed a higher leve1 of expression of chloroplast genes compared with that of the wild type. We discuss the possible function of CND41 as a negative regulator of chloroplast gene expression.

The DNA-binding protease, CND41, and the degradation of ribulose-1,5-bisphosphate carboxylase/oxygenase in senescent leaves of tobacco

“…Previous research indicated that CND41 has DNA-binding as well as aspartic protease activity. Our attempts to identify the physiological functions of CND41 using antisense CND41 tobacco lines (line R28 contained approximately 50% of the CND41 protein found in the wild type, and line R22 accumulated approximately 20%) indicated that both transformants contained more chlorophyll and showed retarded senescence of old leaves at flowering time compared with the wild type (Nakano et al 1997(Nakano et al , 2003. This gave rise to the hypothesis that CND41 has a function in protein turnover in senescent leaves.…”

“…Samsun NN; lines R22, R28) plants with a reduced amount of CND41 were used in this experiment (Nakano et al 1997). Transgenic tobacco transformed with modified pBI121 vector in which the b-glucuronidase gene was removed was used as the control (X6).…”

“…CND41 is a novel protein isolated from the chloroplast nucleoid of cultured tobacco cells (Nakano et al 1997;Murakami et al 2000). Previous research indicated that CND41 has DNA-binding as well as aspartic protease activity.…”

Phosphorylation by protein kinase CKII modulates the DNA-binding activity of a chloroplast nucleoid-associated protein

“…Three other DNA-binding, chloroplast nucleoid proteins have been previously described, PEND, CND41, and DCP68 (Sato et al 1993;Nakano et al 1997;Chi-Ham et al 2002). While currently nothing is known about the effects of phosphorylation on PEND and CND41, dephosphorylation by alkaline phosphatase affects the binding of purified DCP68 to DNA in vitro (Chi-Ham et al 2002).…”

Molecular Cloning and Immunochemical Characterization of a Novel Major Japanese Cedar Pollen Allergen Belonging to the Aspartic Protease Family

“…2b). Other plant aspartic proteases that lack the plant-specific insert have been found in some plants such as rice [47], tobacco [48] and members of the Arabidopsis family [46]. CPA63 also possesses a putative signal peptide sequence (fig.…”