Provided are compositions comprising polynucleotides encoding modified diacylglycerol acyltransferase-1 (DGAT1) polypeptides having improved properties, such as increased enzymatic activity and/or increased stability. Plants, plant cells, seed, grain and comprising the polynucleotides are provided which have one or more of increased fatty acid or protein content. Methods of generating the polynucleotides in plant cells include transformation and genetic modification. Methods of employing the polynucleotides in plants, methods for increasing DGAT1 activity in a plant, and methods for increasing fatty acid content or protein content in a plant are provided.