High impact information on APT1

• The implications of a second, differentially expressed APRTase with affinity for both adenine and cytokinin are discussed [1].
• The APT1 protein is homologous to SABRE and KIP, Arabidopsis proteins of unknown function involved in the elongation of root cortex cells and pollen tubes, respectively [2].
• The mutation was genetically mapped to chromosome I and lies within 6 cM of the phenotypic marker dis2, indicating that the mutation affects the APT1 gene, a result confirmed by sequencing of mutant alleles [3].
• Four mutants of Arabidopsis thaliana that are deficient in adenine phosphoribosyl transferase (APRT) activity have been isolated by selecting for germination of seeds and growth of the plantlets on a medium containing 2,6-diaminopurine (DAP), a toxic analog of adenine [3].
• We have now used electron microscopy to define the effects of APT1 deficiency on pollen development to determine whether the changes might be attributed to adenine or cytokinin metabolism [4].

Biological context of APT1

• An Arabidopsis thaliana mutant lacking the major APT isoform, APT1, is male sterile due to defects soon after meiosis [4].
• Taken together our results suggest that APT1 deficiency causes a general metabolic decrease in energy metabolism, due to the lack of adenine recycling into adenylate nucleotides, which ultimately leads to pollen abortion [4].

References