The MMAB Knockout Raji Polyclonal Cells represent a CRISPR/Cas9-edited human B lymphocyte population engineered for targeted disruption of the MMAB gene. Derived from the Raji cell line, this polyclonal knockout model abolishes expression of the mitochondrial cobalamin adenosyltransferase enzyme, providing a powerful tool to investigate disorders of cobalamin metabolism. The mixed knockout cell pool retains the genetic and phenotypic heterogeneity inherent to polyclonal editing, enabling robust assessment of MMAB-dependent functions in a physiological context.
Raji cells are a well-characterized suspension B lymphocyte line originating from an EBV-positive Burkitt??s lymphoma. They endogenously express markers such as CD19 and CD20, reflecting their mature B cell origin. As a model for immune cell biology, Raji cells exhibit rapid proliferation and are amenable to a wide array of genetic and biochemical manipulations, making them an ideal chassis for studying metabolic pathways that intersect with immune function.
MMAB encodes a mitochondrial ATP:cob(I)alamin adenosyltransferase, which catalyzes the final step in adenosylcobalamin (AdoCbl) biosynthesis. AdoCbl functions as an essential cofactor for methylmalonyl-CoA mutase (MUT), the enzyme responsible for isomerizing methylmalonyl-CoA to succinyl-CoA. This reaction is a key node in the catabolism of propionate, branched-chain amino acids, and odd-chain fatty acids. MMAB activity is regulated by intracellular cobalamin availability and mitochondrial biogenesis programs. It physically interacts with the chaperone MMAA and with MUT to ensure efficient cofactor delivery. Disruption of MMAB thus impairs MUT activation, leading to accumulation of methylmalonyl-CoA and its hydrolysis product methylmalonic acid, while depleting succinyl-CoA pools required for the tricarboxylic acid cycle.
In the Raji B lymphocyte background, MMAB knockout generates a model that dissects the intersection between mitochondrial one-carbon metabolism and immune cell homeostasis. Because Raji cells maintain active mitochondrial respiration, the loss of MMAB permits examination of how impaired AdoCbl synthesis influences cell proliferation, survival, and metabolic adaptation in a lymphoma-relevant context. Moreover, the expression of B cell surface markers allows for concurrent analysis of immune-related phenotypes alongside metabolic dysfunction.
These MMAB knockout cells are ideally suited for dissecting the molecular pathology of cblB-type methylmalonic aciduria, including investigations into vitamin B12 metabolic trafficking and mitochondrial energy failure. They can be employed in metabolic rescue screens, where restoration of AdoCbl synthesis is monitored by adenosyltransferase activity assays or LC-MS?Cbased quantitation of methylmalonic acid. Proliferation assays under varying cobalamin concentrations provide insight into B12-dependent growth, while metabolic flux analysis reveals rerouting of propionate-derived carbons. Flow cytometric profiling of CD19 and CD20 maintains immune identity, enabling concurrent immunophenotypic and metabolic assessments. For further information, please contact Ascent Research.
