I think i could give some points about apps dba resposibilities

1. User Account administration .

add/delete users and password administration.
define levels of access.
Define users (general,advanced,developer,dba etc) & what limits are on those accounts.
passoword administration

2. Quota management.

3. Support user getting information out of db

4. Resource consumption

5. Monitoring database

6. Proactive on long running queries / get the long running query from database and tune it .

thanks