Four genes, A622, NBB1, PMT, and QPT, can be influenced for increasing nicotinic alkaloid levels in Nicotiana plants, as well as for synthesizing nicotinic alkaloids in non-nicotine producing plants and cells. In particular, overexpressing one or more of A622, NBB1, PMT, and QPT may be used to increase nicotine and nicotinic alkaloid levels in tobacco plants. Non-nicotine producing cells can be engineered to produce nicotine and related compounds by overexpressing A622 and NBB1.