Siam's research interests are in cell cycle regulation and how genomic integrity is maintained during DNA replication. She has addressed these topics by studying replication origins in different model systems, and by examining the interaction of cell cycle regulatory proteins with different elements in the replication origin. She is interested in the model bacterium caulobacter crescentus, as she believes this model bacterium will help her analyze how cell cycle regulation results in the replication competent and non-replication competent progeny. She has also focused on the closely related bacterium Rickettsia prowazekii and proposed a similar model for the regulation of replication at the replication origin.