Full Text Journal Articles by
Author Charles Packianathan


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Selective regulation of human TRAAK channels by biologically active phospholipids.

Samantha Schrecke, Yun Zhu, Jacob W McCabe, Mariah Bartz, Charles Packianathan, Minglei Zhao, Ming Zhou, David Russell, Arthur Laganowsky,

TRAAK is an ion channel from the two-pore domain potassium (K2P) channel family with roles in maintaining the resting membrane potential and fast action potential conduction. Regulated by a wide range of physical and chemical stimuli, the affinity and selectivity of K2P4.1 toward lipids remains poorly understood. Here we show ... Read more >>

Nat Chem Biol (Nature chemical biology)
[2020, :]

Cited: 0 times

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Structures of two ArsR As(III)-responsive transcriptional repressors: Implications for the mechanism of derepression.

Chandrasekaran Prabaharan, Palani Kandavelu, Charles Packianathan, Barry P Rosen, Saravanamuthu Thiyagarajan,

ArsR As(III)-responsive transcriptional repressors, members of the ArsR/SmtB family of metalloregulatory proteins, have been characterized biochemically but, to date, no As(III)-bound structure has been solved. Here we report two crystal structures of ArsR repressors from Acidithiobacillus ferrooxidans (AfArsR) and Corynebacterium glutamicum (CgArsR) in the As(III)-bound form. AfArsR crystallized in P21 ... Read more >>

J Struct Biol (Journal of structural biology)
[2019, 207(2):209-217]

Cited: 0 times

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The Structure of an As(III) S-Adenosylmethionine Methyltransferase with 3-Coordinately Bound As(III) Depicts the First Step in Catalysis.

Charles Packianathan, Palani Kandavelu, Barry P Rosen,

Arsenic is a ubiquitous environmental toxic substance and a Class 1 human carcinogen. Arsenic methylation by the enzyme As(III) S-adenosylmethionine (SAM) methyltransferase (ArsM in microbes or AS3MT in animals) detoxifies As(III) in microbes but transforms it into more toxic and potentially more carcinogenic methylated species in humans. We previously proposed ... Read more >>

Biochemistry (Biochemistry)
[2018, 57(28):4083-4092]

Cited: 2 times

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Reorientation of the Methyl Group in MAs(III) is the Rate-Limiting Step in the ArsM As(III) S-Adenosylmethionine Methyltransferase Reaction.

Charles Packianathan, Jiaojiao Li, Palani Kandavelu, Banumathi Sankaran, Barry P Rosen,

The most common biotransformation of trivalent inorganic arsenic (As(III)) is methylation to mono-, di-, and trimethylated species. Methylation is catalyzed by As(III) S-adenosylmethionine (SAM) methyltransferase (termed ArsM in microbes and AS3MT in animals). Methylarsenite (MAs(III)) is both the product of the first methylation step and the substrate of the second ... Read more >>

ACS Omega (ACS omega)
[2018, 3(3):3104-3112]

Cited: 2 times

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Arsenic methylation by a novel ArsM As(III) S-adenosylmethionine methyltransferase that requires only two conserved cysteine residues.

Ke Huang, Yan Xu, Charles Packianathan, Fan Gao, Chuan Chen, Jun Zhang, Qirong Shen, Barry P Rosen, Fang-Jie Zhao,

Arsenic (As) biomethylation is an important component of the As biogeochemical cycle that can influence As toxicity and mobility in the environment. Biomethylation of As is catalyzed by the enzyme arsenite (As[III]) S-adenosylmethionine methyltransferase (ArsM). To date, all identified ArsM orthologs with As(III) methylation activities have four conserved cysteine residues, ... Read more >>

Mol Microbiol (Molecular microbiology)
[2018, 107(2):265-276]

Cited: 5 times

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Nonsynonymous Polymorphisms in the Human AS3MT Arsenic Methylation Gene: Implications for Arsenic Toxicity.

Jiaojiao Li, Charles Packianathan, Toby G Rossman, Barry P Rosen,

Arsenic methylation, the primary biotransformation in the human body, is catalyzed by the enzyme As(III) S-adenosylmethionine (SAM) methyltransferases (hAS3MT). This process is thought to be protective from acute high-level arsenic exposure. However, with long-term low-level exposure, hAS3MT produces intracellular methylarsenite (MAs(III)) and dimethylarsenite (DMAs(III)), which are considerably more toxic than ... Read more >>

Chem. Res. Toxicol. (Chemical research in toxicology)
[2017, 30(7):1481-1491]

Cited: 2 times

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Pathway of human AS3MT arsenic methylation.

Dharmendra S Dheeman, Charles Packianathan, Jitesh K Pillai, Barry P Rosen,

A synthetic gene encoding human As(III) S-adenosylmethionine (SAM) methyltransferase (hAS3MT) was expressed, and the purified enzyme was characterized. The synthetic enzyme is considerably more active than a cDNA-expressed enzyme using endogenous reductants thioredoxin (Trx), thioredoxin reductase (TR), NADPH, and reduced glutathione (GSH). Each of the seven cysteines (the four conserved ... Read more >>

Chem. Res. Toxicol. (Chemical research in toxicology)
[2014, 27(11):1979-1989]

Cited: 40 times

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A disulfide-bond cascade mechanism for arsenic(III) S-adenosylmethionine methyltransferase.

Kavitha Marapakala, Charles Packianathan, A Abdul Ajees, Dharmendra S Dheeman, Banumathi Sankaran, Palani Kandavelu, Barry P Rosen,

Methylation of the toxic metalloid arsenic is widespread in nature. Members of every kingdom have arsenic(III) S-adenosylmethionine (SAM) methyltransferase enzymes, which are termed ArsM in microbes and AS3MT in animals, including humans. Trivalent arsenic(III) is methylated up to three times to form methylarsenite [MAs(III)], dimethylarsenite [DMAs(III)] and the volatile trimethylarsine ... Read more >>

Acta Crystallogr. D Biol. Crystallogr. (Acta crystallographica. Section D, Biological crystallography)
[2015, 71(Pt 3):505-515]

Cited: 16 times

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Crystallization and preliminary X-ray crystallographic studies of CrArsM, an arsenic(III) S-adenosylmethionine methyltransferase from Chlamydomonas reinhardtii.

Charles Packianathan, Jitesh K Pillai, Ahmed Riaz, Palani Kandavelu, Banumathi Sankaran, Barry P Rosen,

Arsenic is one the most toxic environmental substances. Arsenic is ubiquitous in water, soil and food, and ranks first on the Environmental Protection Agency's Superfund Priority List of Hazardous Substances. Arsenic(III) S-adenosylmethionine methyltransferases (AS3MT in animals and ArsM in microbes) are key enzymes of arsenic biotransformation, catalyzing the methylation of ... Read more >>

Acta Crystallogr F Struct Biol Commun (Acta crystallographica. Section F, Structural biology communications)
[2014, 70(Pt 10):1385-1388]

Cited: 2 times

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High-throughput screening-compatible assays of As(III) S-adenosylmethionine methyltransferase activity.

Hui Dong, Wenzhong Xu, Jitesh K Pillai, Charles Packianathan, Barry P Rosen,

Arsenic is a naturally existing toxin and carcinogen. As(III) S-adenosylmethionine methyltransferases (AS3MT in mammals and ArsM in microbes) methylate As(III) three times in consecutive steps and play a central role in arsenic metabolism from bacteria to humans. Current assays for arsenic methylation are slow, laborious, and expensive. Here we report ... Read more >>

Anal Biochem (Analytical biochemistry)
[2015, 480:67-73]

Cited: 3 times

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Determinants of the tumor suppressor INPP4B protein and lipid phosphatase activities.

Sandra M Lopez, Myles C Hodgson, Charles Packianathan, Ozlem Bingol-Ozakpinar, Fikriye Uras, Barry P Rosen, Irina U Agoulnik,

The tumor suppressor INPP4B is an important regulator of phosphatidyl-inositol signaling in the cell. Reduced INPP4B expression is associated with poor outcomes for breast, prostate, and ovarian cancer patients. INPP4B contains a CX5R catalytic motif characteristic of dual-specificity phosphatases, such as PTEN. Lipid phosphatase activity of INPP4B has previously been ... Read more >>

Biochem Biophys Res Commun (Biochemical and biophysical research communications)
[2013, 440(2):277-282]

Cited: 7 times

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Identification of an S-adenosylmethionine (SAM) dependent arsenic methyltransferase in Danio rerio.

Mohamad Hamdi, Masafumi Yoshinaga, Charles Packianathan, Jie Qin, Janell Hallauer, Joseph R McDermott, Hung-Chi Yang, Kan-Jen Tsai, Zijuan Liu,

Arsenic methylation is an important cellular metabolic process that modulates arsenic toxicity and carcinogenicity. Biomethylation of arsenic produces a series of mono-, di- and tri-methylated arsenic metabolites that can be detected in tissues and excretions. Here we report that zebrafish exposed to arsenite (As(III)) produces organic arsenicals, including MMA(III), MMA(V) ... Read more >>

Toxicol Appl Pharmacol (Toxicology and applied pharmacology)
[2012, 262(2):185-193]

Cited: 17 times

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Structure of an As(III) S-adenosylmethionine methyltransferase: insights into the mechanism of arsenic biotransformation.

A Abdul Ajees, Kavitha Marapakala, Charles Packianathan, Banumathi Sankaran, Barry P Rosen,

Enzymatic methylation of arsenic is a detoxification process in microorganisms but in humans may activate the metalloid to more carcinogenic species. We describe the first structure of an As(III) S-adenosylmethionine methyltransferase by X-ray crystallography that reveals a novel As(III) binding domain. The structure of the methyltransferase from the thermophilic eukaryotic ... Read more >>

Biochemistry (Biochemistry)
[2012, 51(27):5476-5485]

Cited: 34 times

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Purification, crystallization and preliminary analysis of hemoglobin from rabbit (Oryctolagus cuniculus).

Sigamani Sundaresan, Packianathan Charles, Kamariah Neelagandan, Mondikalipudur Nanjappa Gounder Ponnuswamy,

Hemoglobin (Hb) is a tetrameric protein, which contains four heme prosthetic groups, and each one is associated with a polypeptide chain. Herein, we report the rabbit hemoglobin which has intrinsically high oxygen affinity and possess highest sequence identity with human hemoglobin. The purified hemoglobin has been tried to crystallize in ... Read more >>

Protein Pept. Lett. (Protein and peptide letters)
[2008, 15(3):318-319]

Cited: 1 time

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