The Q188R Mutation in Human Galactose-1-phosphate Uridylyltransferase Acts as a Partial Dominant Negative

摘要: A longstanding goal in the fields of molecular genetics and biochemistry has been to explain how naturally occurring mutations associated with human metabolic disease impair activity enzymes involved. This is particularly complex for composed multiple subunits, because single may exert both intra- intersubunit effects on holoenzyme structure function. We have previously applied a yeast coexpression system galactose-1-phosphate uridylyltransferase, dimeric enzyme galactosemia, investigate impact subunit association function (). Here we describe purification characterization two heterodimers, R333W/wild type (WT) Q188R/WT, revealing that although first exhibits approximately 50% wild-type activity, second only 15% activity. Neither heterodimer varied significantly from wild regard apparent Km either substrate, Q188R/WT but not R333W/WT heterodimers demonstrated increased thermal sensitivity relative enzyme. These results demonstrate time partial dominant negative effect caused by mutation uridylyltransferase.