Howto go to beginning of line in tmux after remapping prefix to CTRL+A?

following the suggestion in this Archlinux wiki, in the page about tmux I remapped the command key prefix to C-a, to mimic GNU screen and to have something easier on the keyboard than C-b. So my .tmux.conf became this:

set -g default-terminal "screen-256color"
unbind C-b
set -g prefix C-a
set-window-option -g mode-keys vi
bind h select-pane -L
bind j select-pane -D
bind k select-pane -U
bind l select-pane -R

However, while in screen it was possible to use C-a a to jump to the beginning of line, this does not work any more in tmux. As a sidenote, I'm using iTerm2 without the tmux integration.

Does anybody know how to solve this?

Thanks!

You need to tell tmux that Prefix+a should send the prefix key to the program running in the current pane:

bind a send-prefix