BioCyc

Very good metabolism database.

Some things that they have of interest which may not be on NCBI:

Hits a free login wall after a few IP hits. And just a very normal casually browsing number of hits. What is this bullshit?

Their YouTube: www.youtube.com/channel/UCR9QDQ_9_N4isZV_YRQg9tA has some good tutorials.

Database of promoter.

E.g. for E. Coli K-12 MG1655: biocyc.org/group?id=:ALL-PROMOTERS&orgid=ECOLI For some context see e. Coli K-12 MG1655 gene thrL + e. Coli K-12 MG1655 gene thrA + thrB + thrC all of which are in the same transcription unit.